@article {604675,
	title = {MPI_XSTAR: MPI-based Parallelization of the XSTAR Photoionization Program},
	journal = {PASP},
	volume = {130},
	number = {984},
	year = {2018},
	pages = {024501},
	abstract = {We describe a program for the parallel implementation of multiple runs of XSTAR, a photoionization code that is used to predict the physical properties of an ionized gas from its emission and/or absorption lines. The parallelization program, called MPI_XSTAR, has been developed and implemented in the C++ language by using the Message Passing Interface (MPI) protocol, a conventional standard of parallel computing. We have benchmarked parallel multiprocessing executions of XSTAR, using MPI_XSTAR, against a serial execution of XSTAR, in terms of the parallelization speedup and the computing resource efficiency. Our experience indicates that the parallel execution runs significantly faster than the serial execution, however, the efficiency in terms of the computing resource usage decreases with increasing the number of processors used in the parallel computing.},
	url = {http://iopscience.iop.org/article/10.1088/1538-3873/aa9dff/pdf},
	author = {Danehkar, Ashkbiz and Nowak, Michael A and Lee, Julia C. and Randall K Smith}
}
@article {604674,
	title = {Discovery of an Ultraviolet Counterpart to an Ultrafast X-Ray Outflow in the Quasar PG 1211+143},
	journal = {The Astrophysical Journal},
	volume = {853},
	number = {2},
	year = {2018},
	pages = {166},
	abstract = {We observed the quasar PG 1211+143 using the Cosmic Origins Spectrograph on the Hubble Space Telescope in 2015 April as part of a joint campaign with the Chandra X-ray Observatory and the Jansky Very Large Array. Our ultraviolet spectra cover the wavelength range 912{\textendash}2100 {\r A}. We find a broad absorption feature (\~{} 1080 {km} {{{s}}}-1) at an observed wavelength of 1240 {\r A}. Interpreting this as H I Lyα, in the rest frame of PG 1211+143 (z = 0.0809), this corresponds to an outflow velocity of -16,980 {km} {{{s}}}-1\&nbsp;(outflow redshift {z}{out}\~{} -0.0551), matching the moderate ionization X-ray absorption system detected in our Chandra observation and reported previously by Pounds et al. With a minimum H I column density of {log} {N}{{H}{{I}}}\&gt; 14.5, and no absorption in other UV resonance lines, this Lyα absorber is consistent with arising in the same ultrafast outflow as the X-ray absorbing gas. The Lyα feature is weak or absent in archival ultraviolet spectra of PG 1211+143, strongly suggesting that this absorption is transient, and intrinsic to PG 1211+143. Such a simultaneous detection in two independent wavebands for the first time gives strong confirmation of the reality of an ultrafast outflow in an active galactic nucleus.},
	url = {http://iopscience.iop.org/article/10.3847/1538-4357/aaa42b/pdf},
	author = {Kriss, Gerard A. and Lee, Julia C. and Danehkar, Ashkbiz and Nowak, Michael A. and Fang, Taotao and Hardcastle, Martin J.; and Neilsen, Joseph and Young, Andrew}
}
@article {604673,
	title = {The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy},
	journal = {The Astrophysical Journal},
	volume = {853},
	year = {2018},
	pages = {165},
	abstract = {We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create XSTAR photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately -17,300 km s-1\&nbsp;(outflow redshift zout\&nbsp;\~{} -0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter {log}ξ \~{} 2.9 {erg} {{{s}}}-1\&nbsp;{cm} and column density {log}{N}{{H}}\~{} 21.5 {{cm}}-2. This corresponds to a stable region of the absorber{\textquoteright}s thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately -16,980 km s-1\&nbsp;detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.},
	url = {http://iopscience.iop.org/article/10.3847/1538-4357/aaa427/pdf},
	author = {Danehkar, Ashkbiz and Nowak, Michael A and Lee, Julia C. and Kriss, Gerard A and Young, Andrew J. and Hardcastle, Martin J. and Chakravorty, Susmita and Fang, Taotao and Neilsen, Joseph and Rahoui, Farid and Smith, Randall K.}
}
@article {604670,
	title = {Chandra X-ray spectroscopy of focused wind in the Cygnus X-1 system. II. The non-dip spectrum in the low/hard state - modulations with orbital phase},
	journal = {Astronomy \& Astrophysics},
	volume = {590},
	number = {590},
	year = {2016},
	pages = {A114},
	abstract = {Accretion onto the black hole in the system HDE 226868/Cygnus X-1 is powered by the strong line-driven stellar wind of the O-type donor star. We study the X-ray properties of the stellar wind in the hard state of Cyg X-1, as determined using data from the Chandra High Energy Transmission Gratings. Large density and temperature inhomogeneities are present in the wind, with a fraction of the wind consisting of clumps of matter with higher density and lower temperature embedded in a photoionized gas. Absorption dips observed in the light curve are believed to be caused by these clumps. This work concentrates on the non-dip spectra as a function of orbital phase. The spectra show lines of H-like and He-like ions of S, Si, Na, Mg, Al, and highly ionized Fe (Fe xvii{\textendash}Fe xxiv). We measure velocity shifts, column densities, and thermal broadening of the line series. The excellent quality of these five observations allows us to investigate the orbital phase-dependence of these parameters. We show that the absorber is located close to the black hole. Doppler shifted lines point at a complex wind structure in this region, while emission lines seen in some observations are from a denser medium than the absorber. The observed line profiles are phase-dependent. Their shapes vary from pure, symmetric absorption at the superior conjunction to P Cygni profiles at the inferior conjunction of the black hole},
	url = {https://www.aanda.org/articles/aa/pdf/2016/06/aa22490-13.pdf},
	author = {Mi{\v s}kovi{\v c}ov{\'a}, Ivica and Hell, Natalie and Hanke, Manfred and Nowak, Michael A. and Pottschmidt, Katja and Schulz, Norbert S and Grinberg, Victoria and Duro, Refiz and Madej, Oliwia K and Lohfink, Anne M and Rodriguez, J{\'e}r{\^o}me and Cadolle Bel, Marion and Bodaghee, Arash and Tomsick, John A and Lee, Julia C. and Brown, Gregory V and J{\"o}rn Wilms}
}
@conference {604576,
	title = {A Survey of Spin and Relativistic Phenomena in AGN},
	booktitle = {Suzaku-MAXI 2014: Expanding the Frontiers of the X-ray Universe},
	year = {2014},
	pages = {285},
	abstract = {Relativistically broadened spectral features have now been seen in the X-ray spectra of many active galactic nuclei (AGN) and Galactic Black Hole Binaries (GBHBs). Investigations of these features allow us to probe the physics of the innermost accretion flow, the geometry of the still-mysterious hard X-ray source, and the spacetime metric of the black hole itself. We conducted a Suzaku Key Project (AO4-AO6) that, through very deep observations, has enabled detailed studies of strong gravitational physics in five AGN. This has been the first observational census of supermassive black hole (SMBH) spin ever conducted, and acts as a crucial pathfinder study for one of the principal scientific goals of the Astro-H and ATHENA missions. In addition to elucidating the role of black hole spin as an energy source in astrophysics, these data have given us our first glimpse at the spin distribution of the local SMBH population. Our deep Suzaku observations have yielded spin constraints for three of the five AGN studied, all of which show medium-to-high prograde spin values.},
	url = {http://wwwxray.ess.sci.osaka-u.ac.jp/SuzakuMAXI2014/pdf/2014SM_conf_P285-P290.pdf},
	author = {LW Brenneman and CS Reynolds and AC Fabian and M A Nowak and RC Reis and A Lohfink and JM Miller and K Iwasawa and R Mushotzky and M Volonteri and K Nandra and Lee, J. C.}
}
@conference {604575,
	title = {X-ray transmission and reflection through a Compton-thick medium via Monte-Carlo simulations},
	booktitle = {Acta Polytechnica},
	volume = {54},
	number = {3},
	year = {2014},
	pages = {177-182},
	abstract = {The spectral shape of an X-ray source strongly depends on the amount and distribution of the surrounding material. The spectrum of a primary source which is located in an optically thin medium with respect to Compton scattering is mainly modified by photo absorption in the lower energy range and is almost unaltered above ~ 10 keV. This picture changes when the source is obscured by gas exceeding hydrogen column densities of ~ 1024cm-2. At this degree of absorption it is likely that photons are scattered at least twice before leaving the medium. The multiple scatterings lead to a lack of photons in the high energy range of the resulting spectrum as well as to an accumulation of photons at moderate energies forming the so-called Compton-bump. The shape of the fluorescent lines also changes since scattered line photons form several Compton-shoulders which are very prominent especially for Compton-thick sources. Using a Monte Carlo method, we demonstrate the importance of Compton scattering for high column densities. For that purpose, we compare our results with existing absorption models that do not consider Compton scattering. These calculations will be implemented in a prospective version of the\&nbsp;tbabs\&nbsp;absorption model including an analytic evaluation of the strength of the fluorescent lines.},
	url = {https://ojs.cvut.cz/ojs/index.php/ap/article/view/AP.2014.54.0177/2105},
	author = {Wiebke Eikmann and J{\"o}rn Wilms and Randall K Smith and Lee, Julia C.}
}
@article {604574,
	title = {Optical and near-infrared spectroscopy of the black hole GX 339-4 - II. The spectroscopic content in the low/hard and high/soft states},
	journal = {Monthly Notices of the Royal Astronomical Society},
	volume = {442},
	number = {2},
	year = {2014},
	pages = {1610-1618},
	abstract = {As a complement to our optical and near-infrared study of the continuum properties of GX 339-4 in the two hard and one soft state observations made by the ESO/Very Large Telescope (VLT), FOcal Reducer and Spectrograph $\#$2 (FORS2) and infrared spectrometer and array camera (ISAAC) in early 2010, we report here on the results of our spectral line analysis for the same observations. In the soft state, the presence of strong Balmer, Paschen and Brackett emission lines points to the optical and near-infrared spectra stemming from the irradiated chromosphere of the optically thick and geometrically thin accretion disc. Most of these H I\&nbsp;features are still detected in emission in both hard states but are veiled by the compact jets continuum. We also confirm the presence of a broad Hβ absorption feature, prominent in the soft state and shallower in the first hard state, which we argue forms in the deep layers of the optically thick accretion disc. However, this trough is absent in the second hard state, a likely consequence of the formation of a geometrically thick extended envelope that arises above the disc plane and eventually enshrouds the region where the Hβ absorption feature forms. We detect this envelope through the presence of a broad Paβ emission line, which is constant during the first hard state but correlates with the underlying continuum during the second hard state, pointing to changing physical properties. We consider that this behaviour may be consistent with the launch of a thermally driven accretion disc wind during the second hard state.},
	author = {Rahoui, Farid and Coriat, Mickael and Lee, Julia C.}
}
@article {604512,
	title = {A Link between X-Ray Emission Lines and Radio Jets in 4U 1630-47?},
	journal = {The Astrophysical Journal Letters},
	volume = {784},
	number = {1},
	year = {2014},
	pages = {L5},
	abstract = {Recently, D{\'\i}az Trigo et\&nbsp;al. reported an\&nbsp;XMM-Newton\&nbsp;detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. Here we present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the\&nbsp;Chandra\&nbsp;HETGS. While our observations (eight months prior to the\&nbsp;XMM-Newton\&nbsp;campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find no evidence for any relativistic X-ray emission lines. Indeed, despite ~5\&nbsp;{\texttimes}\&nbsp;brighter radio emission, our\&nbsp;Chandra\&nbsp;spectra allow us to place an upper limit on the flux in the blueshifted Fe\&nbsp;XXVI\&nbsp;line that is\&nbsp;\&nbsp;20\&nbsp;{\texttimes}\&nbsp;weaker than the line observed by D{\'\i}az Trigo et\&nbsp;al. We explore several scenarios that could explain our differing results, including variations in the geometry of the jet or a mass-loading process or jet baryon content that evolves with the accretion state of the black hole. We also consider the possibility that the radio emission arises in an interaction between a jet and the nearby interstellar medium, in which case the X-ray emission lines might be unrelated to the radio emission.},
	url = {http://iopscience.iop.org/article/10.1088/2041-8205/784/1/L5/meta},
	author = {Neilsen, Joseph and Coriat, Micka{\"e}l; and Fender, Rob and Lee, Julia C. and Ponti, Gabriele and Tzioumis, Anastasios K and Edwards, Philip G. and Broderick, Jess W.}
}
@article {101701,
	title = {The effects of thermodynamic stability on wind properties in different low mass black hole binary states},
	journal = {Monthly Notices of the Royal Astronomical Society},
	volume = {436},
	year = {2013},
	pages = {560-569},
	abstract = {We present a systematic theory-motivated study of the thermodynamic stability condition as an explanation for the observed accretion disk wind signatures in different states of low mass black hole binaries (BHB). The variability in observed ions is conventionally explained either by variations in the driving mechanisms or the changes in the ionizing flux or due to density effects, whilst thermodynamic stability considerations have been largely ignored. It would appear that the observability of particular ions in different BHB states can be accounted for through simple thermodynamic considerations in the static limit. Our calculations predict that in the disk dominated soft thermal and intermediate states, the wind should be thermodynamically stable and hence observable. On the other hand, in the powerlaw dominated spectrally hard state the wind is found to be thermodynamically unstable for a certain range of 3.55 \&lt;= log \xi \&lt;= 4.20. In the spectrally hard state, a large number of the He-like and H-like ions (including e.g. Fe XXV, Ar XVIII and S XV) have peak ion fractions in the unstable ionization parameter (\xi) range, making these ions undetectable. Our theoretical predictions have clear corroboration in the literature reporting differences in wind ion observability as the BHBs transition through the accretion states Lee et al. 2002; Miller et al. 2008; Neilsen \&amp; Lee 2009; Blum et al. 2010; Ponti et al. 2012; Neilsen \&amp; Homan 2012). While this effect may not be the only one responsible for the observed gradient in the wind properties as a function of the accretion state in BHBs, it is clear that its inclusion in the calculations is crucial to understanding the link between the environment of the compact object and its accretion},
	url = {https://academic.oup.com/mnras/article/436/1/560/974464},
	author = {Chakravorty, Susmita and Lee, Julia C. and Neilsen, Joseph}
}
@article {52966,
	title = {The Ionized Absorber and Nuclear Environment of IRAS 13349+2438: Multi-wavelength insights from coordinated Chandra HETGS, HST STIS, HET, and Spitzer IRS},
	journal = {Monthly Notices of the Royal Astronomical Society},
	volume = {430},
	number = {4},
	year = {2013},
	pages = {2650{\textendash}2679},
	abstract = {We present results from a multi-wavelength infrared (IR)-to-X-ray campaign of the infrared bright (but highly optical-ultraviolet extincted) quasi-stellar object (QSO) IRAS\&nbsp;13349+2438 obtained with the\&nbsp;Chandra\&nbsp;High Energy Transmission Grating Spectrometer (HETGS), the\&nbsp;Hubble Space Telescope\&nbsp;(HST) Space Telescope Imaging Spectrograph (STIS), the Hobby{\textendash}Eberly Telescope (HET) 8\&nbsp;m and the\&nbsp;Spitzer\&nbsp;Infrared Spectrometer (IRS). Based on HET optical spectra of [O III], we refine the redshift of IRAS\&nbsp;13349 to be\&nbsp;z\&nbsp;= 0.108 53. The weakness of the [O III] in combination with strong Fe II\&nbsp;in the HET spectra reveals extreme Eigenvector-1 characteristics in IRAS\&nbsp;13349, but the 2468 km s-1 width of the Hβ line argues against a narrow-line Seyfert\&nbsp;1 classification; on average, IR, optical and optical-ultraviolet (UV) spectra show IRAS\&nbsp;13349 to be a typical QSO. Independent estimates based on the Hβ line width and fits to the IRAS\&nbsp;13349 spectral energy distribution (SED) both give a black hole mass of\&nbsp;MBH\&nbsp;= 109  M⊙. The heavily reddened STIS UV spectra reveal for the first time blueshifted absorption from Ly Α, N V\&nbsp;and C IV, with components at systemic velocities of\&nbsp;-950km/s and -75km/s. The higher velocity UV lines are coincident with the lower ionization (ξ\&nbsp;\~{} 1.6) WA-1 warm absorber lines seen in the X-rays with the HETGS. In addition, a ξ\&nbsp;\~{} 3.4 WA-2 is also required by the data, while a ξ\&nbsp;\~{} 3 WA-3 is predicted by theory and seen at less significance; all detected X-ray absorption lines are blueshifted by \~{} 700-900 km s-1 . Theoretical models comparing different ionizing SEDs reveal that including the UV (i.e. the accretion disc) as part of the ionizing continuum has strong implications for the conclusions one would draw about the thermodynamic stability of the warm absorber. Specific to IRAS\&nbsp;13349, we find that an X-ray{\textendash}UV ionizing SED favours a continuous distribution of ionization states in a smooth flow (this paper) versus discrete clouds in pressure equilibrium (previous work by other authors). Direct detections of dust are seen in both the IR and X-rays. We see weak polycyclic aromatic hydrocarbon (PAH) emission at 7.7\&nbsp;μm and 11.3\&nbsp;μm which may also be blended with forsterite, and 10\&nbsp;μm and 18\&nbsp;μm silicate emission, as well as an Fe L edge at 700 eV indicative of iron-based dust with a dust-to-gas ratio\&nbsp;\&gt;90\&nbsp;per\&nbsp;cent. We develop a geometrical model in which we view the nuclear regions of the QSO along a line of sight that passes through the upper atmosphere of an obscuring torus. This sight line is largely transparent in X-rays since the gas is ionized, but it is completely obscured by dust that blocks a direct view of the UV/optical emission region. In the context of our model, 20\&nbsp;per\&nbsp;cent of the intrinsic UV/optical continuum is scattered into our sight line by the far wall of an obscuring torus. An additional 2.4\&nbsp;per\&nbsp;cent of the direct light, which likely dominates the UV emission, is Thomson-scattered into our line of sight by another off-plane component of highly ionized gas.},
	url = {https://academic.oup.com/mnras/article/430/4/2650/1095269},
	author = {Lee, Julia C. and Kriss, Gerard and Chakravorty, Susmita and Rahoui, Farid and Young, Andrew J. and Brandt, William N. and Hines, Dean C. and Ogle, Patrick M. and Reynolds, Christopher S.}
}
@article {2012MNRAS.421..502N,
	title = {{Accretion disc wind variability in the states of the microquasar GRS 1915+105}},
	journal = {MNRAS},
	volume = {421},
	year = {2012},
	note = {n/a},
	pages = {502-511},
	abstract = {{Continuing our study of the role and evolution of accretion disc winds in the microquasar GRS 1915+105, we present high-resolution spectral variability analysis of the {$\beta$} and {$\gamma$} states with the Chandra High-Energy Transmission Grating Spectrometer. By tracking changes in the absorption lines from the accretion disc wind, we find new evidence that radiation links the inner and outer accretion discs on a range of time-scales. As the central X-ray flux rises during the high-luminosity {$\gamma$} state, we observe the progressive overionization of the wind. In the {$\beta$} state, we argue that changes in the inner disc leading to the ejection of a transient {\textquoteright}baby jet{\textquoteright} also quench the highly ionized wind from the outer disc. Our analysis reveals how the state, structure and X-ray luminosity of the inner accretion disc all conspire to drive the formation and variability of highly ionized accretion disc winds. }},
	doi = {10.1111/j.1365-2966.2011.20329.x},
	author = {{Neilsen}, J. and {Petschek}, A.~J. and {Lee}, J.~C.}
}
@article {2012ApJ...750...71N,
	title = {Radiation Pressure and Mass Ejection in rho-like States of GRS 1915+105},
	journal = {Astrophysical Journal},
	volume = {750},
	year = {2012},
	note = {n/a
},
	month = {may},
	pages = {71},
	abstract = {{We present a unifying scenario to address the physical origin of the diversity of X-ray light curves within the {$\rho$} variability class of the microquasar GRS 1915+105. This {\textquoteright}{\textquoteright}heartbeat{\textquoteright}{\textquoteright} state is characterized by a bright flare that recurs every \~{}50-100 s, but the profile and duration of the flares vary significantly from observation to observation. Based on a comprehensive, phase-resolved study of heartbeats in the Rossi X-ray Timing Explorer archive, we demonstrate that very different X-ray light curves do not require origins in different accretion processes. Indeed, our detailed comparison of the phase-resolved spectra of a double-peaked oscillation and a single-peaked oscillation shows that different cycles can have basically similar X-ray spectral evolution. We argue that all heartbeat oscillations can be understood as the result of a combination of a thermal-viscous radiation pressure instability, a local Eddington limit in the disk, and a sudden, radiation-pressure-driven evaporation or ejection event in the inner accretion disk. This ejection appears to be a universal, fundamental part of the {$\rho$} state, and is largely responsible for a hard X-ray pulse seen in the light curve of all cycles. We suggest that the detailed shape of oscillations in the mass accretion rate through the disk is responsible for the phenomenological differences between different {$\rho$}-type light curves, and we discuss how future time-dependent simulations of disk instabilities may provide new insights into the role of radiation pressure in the accretion flow. }
},
	doi = {10.1088/0004-637X/750/1/71},
	author = {Neilsen, J. and Remillard, R.~A. and Lee, J.~C.}
}
@article {2012ApJ...751...53A,
	title = {{Multi-wavelength Observations of the Radio Magnetar PSR J1622-4950 and Discovery of Its Possibly Associated Supernova Remnant}},
	journal = {The Astrophysical Journal},
	volume = {751},
	year = {2012},
	note = {n/a},
	month = {may},
	pages = {53},
	abstract = {{We present multi-wavelength observations of the radio magnetar PSR J1622-4950 and its environment. Observations of PSR J1622-4950 with Chandra (in 2007 and 2009) and XMM (in 2011) show that the X-ray flux of PSR J1622-4950 has decreased by a factor of \~{}50 over 3.7 years, decaying exponentially with a characteristic time of {$\tau$} = 360 {\plusmn} 11 days. This behavior identifies PSR J1622-4950 as a possible addition to the small class of transient magnetars. The X-ray decay likely indicates that PSR J1622-4950 is recovering from an X-ray outburst that occurred earlier in 2007, before the 2007 Chandra observations. Observations with the Australia Telescope Compact Array show strong radio variability, including a possible radio flaring event at least one and a half years after the 2007 X-ray outburst that may be a direct result of this X-ray event. Radio observations with the Molonglo Observatory Synthesis Telescope reveal that PSR J1622-4950 is 8{\textquoteright} southeast of a diffuse radio arc, G333.9+0.0, which appears non-thermal in nature and which could possibly be a previously undiscovered supernova remnant (SNR). If G333.9+0.0 is an SNR then the estimates of its size and age, combined with the close proximity and reasonable implied velocity of PSR J1622-4950, suggest that these two objects could be physically associated. }},
	doi = {10.1088/0004-637X/751/1/53},
	author = {{Anderson}, G.~E. and {Gaensler}, B.~M. and {Slane}, P.~O. and {Rea}, N. and {Kaplan}, D.~L. and {Posselt}, B. and {Levin}, L. and {Johnston}, S. and {Murray}, S.~S. and {Brogan}, C.~L. and {Bailes}, M. and {Bates}, S. and {Benjamin}, R.~A. and {Bhat}, N.~D.~R. and {Burgay}, M. and {Burke-Spolaor}, S. and {Chakrabarty}, D. and {D{\textquoteright}Amico}, N. and {Drake}, J.~J. and {Esposito}, P. and {Grindlay}, J.~E. and {Hong}, J. and {Israel}, G.~L. and {Keith}, M.~J. and {Kramer}, M. and {Lazio}, T.~J.~W. and {Lee}, J.~C. and {Mauerhan}, J.~C. and {Milia}, S. and {Possenti}, A. and {Stappers}, B. and {Steeghs}, D.~T.~H.}
}
@article {2012MNRAS.422.2202R,
	title = {{Optical and near-infrared spectroscopy of the black hole GX 339-4 - I. A focus on the continuum in the low/hard and high/soft states}},
	journal = {\mnras},
	volume = {422},
	year = {2012},
	note = {n/a},
	pages = {2202-2212},
	abstract = {{The microquasar GX 339-4, known to exhibit powerful compact jets that dominate its radio to near-infrared emission, entered an outburst in 2010 for the fifth time in about 15 yr. An extensive radio to X-ray multiwavelength campaign was immediately triggered, and we report here on European Southern Observatory/FORS2+ISAAC optical and near-infrared spectroscopic observations, supported by Australia Telescope Compact Array radio and Rossi X-ray Timing Experiment/Swift X-ray quasi-simultaneous data. GX 339-4 was observed at three different epochs, once in the soft state and twice in the hard state. In the soft state, the optical and near-infrared continuum is largely consistent with the Raleigh-Jeans tail of a thermal process. As an explanation, we favour irradiation of the outer accretion disc by its inner regions, enhanced by disc warping. An excess is also present at low frequencies, likely due to an M subgiant companion star. During the first hard state, the optical/near-infrared continuum is well described by the optically thin synchrotron emission of the compact jet combined with disc irradiation and perhaps another component peaking in the ultraviolet. The spectral break where the jet transits from the optically thick to thin regimes, located below 1.20 {\times} 10$^{14}$ Hz, is not detected and the extension of the optically thin synchrotron is consistent with the 3-50 keV spectrum. In contrast, the emission during the second hard state is more difficult to understand and points towards a more complex jet continuum. In both cases, the near-infrared continuum is found to be variable at time-scales at least as short as 20 s, although these variabilities are smoothed out beyond a few hundred seconds. This implies rapid variations - in flux and frequency - of the location of the spectral break, i.e. dramatic short time-scale changes of the physical conditions at the base of the jet, such as the magnetic field and/or the base radius. $^{ a }$ Same as DISKBB. }
},
	doi = {10.1111/j.1365-2966.2012.20763.x},
	author = {{Rahoui}, F. and {Coriat}, M. and {Corbel}, S. and {Cadolle Bel}, M. and {Tomsick}, J.~A. and {Lee}, J.~C. and {Rodriguez}, J. and {Russell}, D.~M. and {Migliari}, S.}
}
@article {2011ApJ...727..105A,
	title = {{Identification of a Population of X-ray-emitting Massive Stars in the Galactic Plane}},
	journal = {\apj},
	volume = {727},
	year = {2011},
	note = {n/a},
	pages = {105},
	abstract = {{We present X-ray, infrared, optical, and radio observations of four previously unidentified Galactic plane X-ray sources: AX J163252-4746, AX J184738-0156, AX J144701-5919, and AX J144547-5931. Detection of each source with the Chandra X-ray Observatory has provided sub-arcsecond localizations, which we use to identify bright infrared counterparts to all four objects. Infrared and optical spectroscopy of these counterparts demonstrate that all four X-ray sources are extremely massive stars, with spectral classifications: Ofpe/WN9 (AX J163252-4746), WN7 (AX J184738-0156 = WR121a), WN7-8h (AX J144701-5919), and OIf$^{+}$ (AX J144547-5931). AX J163252-4746 and AX J184738-0156 are both luminous, hard, X-ray emitters with strong Fe XXV emission lines in their X-ray spectra at \~{}6.7 keV. The multi-wavelength properties of AX J163252-4746 and AX J184738-0156 are not consistent with isolated massive stars or accretion onto a compact companion; we conclude that their X-ray emission is most likely generated in a colliding-wind binary (CWB) system. For both AX J144701-5919 and AX J144547-5931, the X-ray emission is an order of magnitude less luminous and with a softer spectrum. These properties are consistent with a CWB interpretation for these two sources also, but other mechanisms for the generation of X-rays cannot be excluded. There are many other as yet unidentified X-ray sources in the Galactic plane, with X-ray properties similar to those seen for AX J163252-4746, AX J184738-0156, AX J144701-5919, and AX J144547-5931. This may indicate a substantial population of X-ray-emitting massive stars and CWBs in the Milky Way. }
},
	doi = {10.1088/0004-637X/727/2/105},
	author = {{Anderson}, G.~E. and {Gaensler}, B.~M. and {Kaplan}, D.~L. and {Posselt}, B. and {Slane}, P.~O. and {Murray}, S.~S. and {Mauerhan}, J.~C. and {Benjamin}, R.~A. and {Brogan}, C.~L. and {Chakrabarty}, D. and {Drake}, J.~J. and {Drew}, J.~E. and {Grindlay}, J.~E. and {Hong}, J. and {Lazio}, T.~J.~W. and {Lee}, J.~C. and {Steeghs}, D.~T.~H. and {van Kerkwijk}, M.~H.}
}
@article {2011ApJ...729...30M,
	title = {{A Detection of an X-ray Wind and an Ionized Disk in the Chandra HETGS Observation of the Seyfert 2 Galaxy IRAS 18325-5926}},
	journal = {\apj},
	volume = {729},
	year = {2011},
	note = {n/a},
	month = {mar},
	pages = {30},
	abstract = {{We analyze the Chandra High Energy Transmission Grating Spectrometer observation of the Seyfert 2 AGN IRAS 18325-5926. We detect a v = -360$^{+41}$ $_{-66}$ km s$^{-1}$ blueshifted ionized absorber in the X-ray spectrum, with photoionization parameter log {$\xi$} = 2.0$^{+0.1}$ $_{-0.1}$ and hydrogen column density N $_{H}$ = 1.55$^{+0.75}$ $_{-0.38}$ {\times} 10$^{21}$ cm$^{-2}$. The absorber may be a photoionized wind originating in the obscuring torus/global covering around the black hole or outer edge of the accretion disk. The estimated mass outflow rate suggests that the supermassive black hole in IRAS 18325-5926 may significantly affect the large-scale environment of the host galaxy, unless the solid angle subtended by the outflow or the gas filling factor is small. A second warm absorber may be needed to explain the absorption features in the vicinity of the iron K edge, although insufficient counts in the data beyond 7.0 keV make it difficult to assess the nature of the second absorber. Most plausible is a high ionization (log {$\xi$} \~{} 2.3 to 2.6), high column density (N $_{H}$ \~{} 10$^{23}$ cm$^{-2}$) absorber with v \~{} -3000 to 0 km s$^{-1}$, although these parameters are not well constrained. We also examine the broad Fe K emission line in the spectrum, which is likely due to Fe XXV in a highly ionized accretion disk inclined at 25{\deg}, consistent with the XMM-Newton EPIC observations of the emission line. Because we are able to view both the obscuring gas and the accretion disk of IRAS 18325-5926, the surrounding gas of IRAS 18325-5926 may be patchy or we are viewing the system at an angle just grazing the obscuring torus. }
},
	doi = {10.1088/0004-637X/729/1/30},
	author = {{Mocz}, P. and {Lee}, J.~C. and {Iwasawa}, K. and {Canizares}, C.~R.}
}
@article {2011ApJ...736...63R,
	title = {{A Multiwavelength Study of Cygnus X-1: The First Mid-infrared Spectroscopic Detection of Compact Jets}},
	journal = {\apj},
	volume = {736},
	year = {2011},
	note = {n/a},
	pages = {63},
	abstract = {{We report on a Spitzer/InfraRed Spectrograph (mid-infrared), RXTE/PCA+HEXTE (X-ray), and Ryle (radio) simultaneous multiwavelength study of the microquasar Cygnus X-1, which aimed at an investigation of the origin of its mid-infrared emission. Compact jets were present in two out of three observations, and we show that they strongly contribute to the mid-infrared continuum. During the first observation, we detect the spectral break{\mdash}where the transition from the optically thick to the optically thin regime takes place{\mdash}at about 2.9 {\times} 10$^{13}$ Hz. We then show that the jet{\textquoteright}s optically thin synchrotron emission accounts for Cygnus X-1{\textquoteright}s emission beyond 400 keV, although it cannot alone explain its 3-200 keV continuum. A compact jet was also present during the second observation, but we do not detect the break, since it has likely shifted to higher frequencies. In contrast, the compact jet was absent during the last observation, and we show that the 5-30 {$μ$}m mid-infrared continuum of Cygnus X-1 stems from the blue supergiant companion star HD 226868. Indeed, the emission can then be understood as the combination of the photospheric Rayleigh-Jeans tail and the bremsstrahlung from the expanding stellar wind. Moreover, the stellar wind is found to be clumpy, with a filling factor f $_{$\infty$}$ {\ap} 0.09-0.10. Its bremsstrahlung emission is likely anti-correlated to the soft X-ray emission, suggesting an anti-correlation between the mass-loss and mass-accretion rates. Nevertheless, we do not detect any mid-infrared spectroscopic evidence of interaction between the jets and Cygnus X-1{\textquoteright}s environment and/or the companion star{\textquoteright}s stellar wind. }
},
	doi = {10.1088/0004-637X/736/1/63},
	author = {{Rahoui}, F. and {Lee}, J.~C. and {Heinz}, S. and {Hines}, D.~C. and {Pottschmidt}, K. and {Wilms}, J. and {Grinberg}, V.}
}
@article {2011ApJ...737...69N,
	title = {{The Physics of the {\textquoteright}{\textquoteright}Heartbeat{\textquoteright}{\textquoteright} State of GRS 1915+105}},
	journal = {\apj},
	volume = {737},
	year = {2011},
	note = {n/a},
	pages = {69},
	abstract = {{We present the first detailed phase-resolved spectral analysis of a joint Chandra High-Energy Transmission Grating Spectrometer and Rossi X-ray Timing Explorer observation of the {$\rho$} variability class in the microquasar GRS 1915+105. The {$\rho$} cycle displays a high-amplitude, double-peaked flare that recurs roughly every 50 s and is sometimes referred to as the {\textquoteright}{\textquoteright}heartbeat{\textquoteright}{\textquoteright} oscillation. The spectral and timing properties of the oscillation are consistent with the radiation pressure instability and the evolution of a local Eddington limit in the inner disk. We exploit strong variations in the X-ray continuum, iron emission lines, and the accretion disk wind to probe the accretion geometry over nearly six orders of magnitude in distance from the black hole. At small scales (1-10 R $_{g}$), we detect a burst of bremsstrahlung emission that appears to occur when a portion of the inner accretion disk evaporates due to radiation pressure. Jet activity, as inferred from the appearance of a short X-ray hard state, seems to be limited to times near minimum luminosity, with a duty cycle of \~{}10\%. On larger scales (10$^{5}$-10$^{6}$ R $_{g}$), we use detailed photoionization arguments to track the relationship between the fast X-ray variability and the accretion disk wind. For the first time, we are able to show that changes in the broadband X-ray spectrum produce changes in the structure and density of the accretion disk wind on timescales as short as 5 s. These results clearly establish a causal link between the X-ray oscillations and the disk wind and therefore support the existence of a disk-jet-wind connection. Furthermore, our analysis shows that the mass-loss rate in the wind may be sufficient to cause long-term oscillations in the accretion rate, leading to state transitions in GRS 1915+105. }
},
	doi = {10.1088/0004-637X/737/2/69},
	author = {{Neilsen}, J. and {Remillard}, R.~A. and {Lee}, J.~C.}
}
@article {2011ApJ...736..103B,
	title = {{The Spin of the Supermassive Black Hole in NGC 3783}},
	journal = {\apj},
	volume = {736},
	year = {2011},
	note = {n/a},
	month = {aug},
	pages = {103},
	abstract = {{The Suzaku AGN Spin Survey is designed to determine the supermassive black hole spin in six nearby active galactic nuclei (AGNs) via deep Suzaku stares, thereby giving us our first glimpse of the local black hole spin distribution. Here, we present an analysis of the first target to be studied under the auspices of this Key Project, the Seyfert galaxy NGC 3783. Despite complexity in the spectrum arising from a multi-component warm absorber, we detect and study relativistic reflection from the inner accretion disk. Assuming that the X-ray reflection is from the surface of a flat disk around a Kerr black hole, and that no X-ray reflection occurs within the general relativistic radius of marginal stability, we determine a lower limit on the black hole spin of a {\gt}= 0.88 (99\% confidence). We examine the robustness of this result to the assumption of the analysis and present a brief discussion of spin-related selection biases that might affect flux-limited samples of AGNs. }
},
	doi = {10.1088/0004-637X/736/2/103},
	author = {{Brenneman}, L.~W. and {Reynolds}, C.~S. and {Nowak}, M.~A. and {Reis}, R.~C. and {Trippe}, M. and {Fabian}, A.~C. and {Iwasawa}, K. and {Lee}, J.~C. and {Miller}, J.~M. and {Mushotzky}, R.~F. and {Nandra}, K. and {Volonteri}, M.}
}
@article {2011ApJ...738...78X,
	title = {{Using the X-Ray Dust Scattering Halo of Cygnus X-1 to Determine Distance and Dust Distributions}},
	journal = {\apj},
	volume = {738},
	year = {2011},
	note = {n/a},
	pages = {78},
	abstract = {{We present a detailed study of the X-ray dust scattering halo of the black hole candidate Cygnus X-1 based on two Chandra High Energy Transmission Gratings Spectrometer observations. Using 18 different dust models, including one modified by us (eponymously dubbed XLNW), we probe the interstellar medium between us and this source. A consistent description of the cloud properties along the line of sight (LOS) that describes at the same time the halo radial profile, the halo light curves, and the column density from source spectroscopy is best achieved with a small subset of these models. Combining the studies of the halo radial profile and the halo light curves, we favor a geometric distance to Cygnus X-1 of d = 1.81 {\plusmn} 0.09 kpc. Our study also shows that there is a dense cloud, which contributes \~{}50\% of the dust grains along the LOS to Cygnus X-1, located at \~{}1.6 kpc from us. The remainder of the dust along the LOS is close to the black hole binary. }
},
	doi = {10.1088/0004-637X/738/1/78},
	author = {{Xiang}, J. and {Lee}, J.~C. and {Nowak}, M.~A. and {Wilms}, J.}
}
@article {2011ApJ...741L...4E,
	title = {{The Suzaku View of the Disk-Jet Connection in the Low-excitation Radio Galaxy NGC 6251}},
	journal = {\apjl},
	volume = {741},
	year = {2011},
	note = {n/a},
	pages = {L4},
	abstract = {{We present results from an 87 ks Suzaku observation of the canonical low-excitation radio galaxy (LERG) NGC 6251. We have previously suggested that LERGs violate conventional active galactic nucleus unification schemes: they may lack an obscuring torus and are likely to accrete in a radiatively inefficient manner, with almost all of the energy released by the accretion process being channeled into powerful jets. We model the 0.5-20 keV Suzaku spectrum with a single power law of photon index {$\Gamma$} = 1.82$^{+0.04}$ $_{- 0.05}$, together with two collisionally ionized plasma models whose parameters are consistent with the known galaxy- and group-scale thermal emission. Our observations confirm that there are no signatures of obscured, accretion-related X-ray emission in NGC 6251, and we show that the luminosity of any such component must be substantially sub-Eddington in nature. }
},
	doi = {10.1088/2041-8205/741/1/L4},
	author = {{Evans}, D.~A. and {Summers}, A.~C. and {Hardcastle}, M.~J. and {Kraft}, R.~P. and {Gandhi}, P. and {Croston}, J.~H. and {Lee}, J.~C.}
}
@article {2011ApJ...738...78X,
	title = {{Using the X-Ray Dust Scattering Halo of Cygnus X-1 to Determine Distance and Dust Distributions}},
	journal = {\apj},
	volume = {738},
	year = {2011},
	note = {n/a
},
	pages = {78},
	abstract = {{We present a detailed study of the X-ray dust scattering halo of the black hole candidate Cygnus X-1 based on two Chandra High Energy Transmission Gratings Spectrometer observations. Using 18 different dust models, including one modified by us (eponymously dubbed XLNW), we probe the interstellar medium between us and this source. A consistent description of the cloud properties along the line of sight (LOS) that describes at the same time the halo radial profile, the halo light curves, and the column density from source spectroscopy is best achieved with a small subset of these models. Combining the studies of the halo radial profile and the halo light curves, we favor a geometric distance to Cygnus X-1 of d = 1.81 {\plusmn} 0.09 kpc. Our study also shows that there is a dense cloud, which contributes \~{}50\% of the dust grains along the LOS to Cygnus X-1, located at \~{}1.6 kpc from us. The remainder of the dust along the LOS is close to the black hole binary. }
},
	doi = {10.1088/0004-637X/738/1/78},
	author = {{Xiang}, J. and {Lee}, J.~C. and {Nowak}, M.~A. and {Wilms}, J.}
}
@article {2010ApJ...722.1735L,
	title = {{A Chandra Observation of 3C 288{\mdash}Reheating the Cool Core of a 3 keV Cluster from a Nuclear Outburst at z = 0.246}},
	journal = {\apj},
	volume = {722},
	year = {2010},
	note = {n/a},
	pages = {1735-1743},
	abstract = {{We present results from a 42 ks Chandra/ACIS-S observation of the transitional FR I/FR II radio galaxy 3C 288 at z = 0.246. We detect \~{}3 keV gas extending to a radius of \~{}0.5 Mpc with a 0.5-2.0 keV luminosity of 6.6 {\times} 10$^{43}$ erg s$^{-1}$, implying that 3C 288 lies at the center of a poor cluster. We find multiple surface brightness discontinuities in the gas indicative of either a shock driven by the inflation of the radio lobes or a recent merger event. The temperature across the discontinuities is roughly constant with no signature of a cool core, thus disfavoring either the merger cold front or sloshing scenarios. We argue therefore that the discontinuities are shocks due to the supersonic inflation of the radio lobes. If they are shocks, the energy of the outburst is \~{}10$^{60}$ erg, or roughly 30\% of the thermal energy of the gas within the radius of the shock, assuming that the shocks are part of a front produced by a single outburst. The cooling time of the gas is \~{}10$^{8}$ yr, so that the energy deposited by the nuclear outburst could have reheated and efficiently disrupted a cool core. }
},
	doi = {10.1088/0004-637X/722/2/1735},
	author = {{Lal}, D.~V. and {Kraft}, R.~P. and {Forman}, W.~R. and {Hardcastle}, M.~J. and {Jones}, C. and {Nulsen}, P.~E.~J. and {Evans}, D.~A. and {Croston}, J.~H. and {Lee}, J.~C.}
}
@article {2010ApJ...710..859E,
	title = {{The Hard X-ray View of Reflection, Absorption, and the Disk-Jet Connection in the Radio-loud AGN 3C 33}},
	journal = {\apj},
	volume = {710},
	year = {2010},
	note = {n/a},
	month = {feb},
	pages = {859-868},
	abstract = {{We present results from Suzaku and Swift observations of the nearby radio galaxy 3C 33, and investigate the nature of absorption, reflection, and jet production in this source. We model the 0.5-100 keV nuclear continuum with a power law that is transmitted either through one or more layers of pc-scale neutral material, or through a modestly ionized pc-scale obscurer. The standard signatures of reflection from a neutral accretion disk are absent in 3C 33: there is no evidence of a relativistically blurred Fe K{$\alpha$} emission line, and no Compton reflection hump above 10 keV. We find the upper limit to the neutral reflection fraction is R {\l}t} 0.41 for an e-folding energy of 1 GeV. We observe a narrow, neutral Fe K{$\alpha$} line, which is likely to originate at least 2000 R $_{s}$ from the black hole. We show that the weakness of reflection features in 3C 33 is consistent with two interpretations: either the inner accretion flow is highly ionized, or the black-hole spin configuration is retrograde with respect to the accreting material. }
},
	doi = {10.1088/0004-637X/710/1/859},
	author = {{Evans}, D.~A. and {Reeves}, J.~N. and {Hardcastle}, M.~J. and {Kraft}, R.~P. and {Lee}, J.~C. and {Virani}, S.~N.}
}
@article {2010SSRv..157...93L,
	title = {{X-ray Spectroscopy of Astrophysical Dust. A High Spectral Resolution (Re)View and Look to the Future}},
	volume = {157},
	year = {2010},
	note = {n/a},
	pages = {93-101},
	abstract = {{High spectral resolution X-ray instruments on powerful X-ray satellites (e.g. Chandra, XMM-Newton) pointed through dust and gas at bright black holes and neutron stars can be used to study dust and intervening material in unique ways. With the new subfield of Condensed Matter Astrophysics as its goal, I will discuss current efforts to combine techniques and knowledge from condensed matter physics and astrophysics to determine the species-specific quantity and composition of interstellar gas and dust in the ISM and ionized environments. Prospects for improving on this work in future X-ray missions with higher throughput and spectral resolution are also presented in the context of spectral resolution goals for gratings and calorimeters. }
},
	doi = {10.1007/s11214-010-9723-2},
	author = {{Lee}, J.~C.}
}
@article {2010SSRv..157...93L,
	title = {{X-ray Spectroscopy of Astrophysical Dust. A High Spectral Resolution (Re)View and Look to the Future}},
	volume = {157},
	year = {2010},
	note = {n/a},
	pages = {93-101},
	abstract = {{High spectral resolution X-ray instruments on powerful X-ray satellites (e.g. Chandra, XMM-Newton) pointed through dust and gas at bright black holes and neutron stars can be used to study dust and intervening material in unique ways. With the new subfield of Condensed Matter Astrophysics as its goal, I will discuss current efforts to combine techniques and knowledge from condensed matter physics and astrophysics to determine the species-specific quantity and composition of interstellar gas and dust in the ISM and ionized environments. Prospects for improving on this work in future X-ray missions with higher throughput and spectral resolution are also presented in the context of spectral resolution goals for gratings and calorimeters. }
},
	doi = {10.1007/s11214-010-9723-2},
	author = {{Lee}, J.~C.}
}
@article {604699,
	title = {Parallelizing the XSTAR Photoionization Code},
	journal = {Astronomical Data Analysis Software and Systems XVIII},
	volume = {411},
	year = {2009},
	pages = {301},
	abstract = {We describe two means by which XSTAR, a code which computes physical conditions and emission spectra of photoionized gases, has been parallelized. The first is pvmxstar, a wrapper which can be used in place of the serial xstar2xspec script to foster concurrent execution of the XSTAR command line application on independent sets of parameters. The second is pmodel, a plugin for the Interactive Spectral Interpretation System (ISIS) which allows arbitrary components of a broad range of astrophysical models to be distributed across processors during fitting and confidence limits calculations, by scientists with little training in parallel programming. Plugging the XSTAR family of analytic models into pmodel enables multiple ionization states (e.g., of a complex absorber/emitter) to be computed simultaneously, alleviating the often prohibitive expense of the traditional serial approach. Initial performance results indicate that these methods substantially enlarge the problem space to which XSTAR may be applied within practical timeframes.},
	url = {http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2009ASPC..411..301N\&amp;data_type=PDF_HIGH\&amp;whole_paper=YES\&amp;type=PRINTER\&amp;filetype=.pdf},
	author = {Noble, M. S and Li, J. and Young, A., and Lee, J.C.}
}
@article {2009ApJ...690..330H,
	title = {{Chandra X-Ray Spectroscopy of the Focused Wind in the Cygnus X-1 System. I. The Nondip Spectrum in the Low/Hard State}},
	journal = {The Astrophysical Journal},
	volume = {690},
	year = {2009},
	note = {n/a},
	pages = {330-346},
	abstract = {{We present analyses of a 50 ks observation of the supergiant X-ray binary system Cygnus X-1 (Cyg X-1)/HDE226868 taken with the Chandra High Energy Transmission Grating Spectrometer (HETGS). Cyg X-1 was in its spectrally hard state and the observation was performed during superior conjunction of the black hole, allowing for the spectroscopic analysis of the accreted stellar wind along the line of sight. A significant part of the observation covers X-ray dips as commonly observed for Cyg X-1 at this orbital phase, however, here we analyze only the high count rate nondip spectrum. The full 0.5-10 keV continuum can be described by a single model consisting of a disk, a narrow and a relativistically broadened Fe K{$\alpha$} line, and a power-law component, which is consistent with simultaneous Rossi X-Ray Timing Explorer broadband data. We detect absorption edges from overabundant neutral O, Ne, and Fe, and absorption line series from highly ionized ions and infer column densities and Doppler shifts. With emission lines of He-like Mg XI, we detect two plasma components with velocities and densities consistent with the base of the spherical wind and a focused wind. A simple simulation of the photoionization zone suggests that large parts of the spherical wind outside of the focused stream are completely ionized, which is consistent with the low velocities ({\l}t}200 km s$^{-1}$) observed in the absorption lines, as the position of absorbers in a spherical wind at low projected velocity is well constrained. Our observations provide input for models that couple the wind activity of HDE 226868 to the properties of the accretion flow onto the black hole. }},
	doi = {10.1088/0004-637X/690/1/330},
	author = {{Hanke}, M. and {Wilms}, J. and {Nowak}, M.~A. and {Pottschmidt}, K. and {Schulz}, N.~S. and {Lee}, J.~C.}
}
@article {2009Natur.458..481N,
	title = {{Accretion disk winds as the jet suppression mechanism in the microquasar GRS 1915+105}},
	journal = {Nature},
	volume = {458},
	year = {2009},
	note = {n/a},
	month = {mar},
	pages = {481-484},
	abstract = {{Stellar-mass black holes with relativistic jets, also known as microquasars, mimic the behaviour of quasars and active galactic nuclei. Because timescales around stellar-mass black holes are orders of magnitude smaller than those around more distant supermassive black holes, microquasars are ideal nearby {\textquoteleft}laboratories{\textquoteright} for studying the evolution of accretion disks and jet formation in black-hole systems. Whereas studies of black holes have revealed a complex array of accretion activity, the mechanisms that trigger and suppress jet formation remain a mystery. Here we report the presence of a broad emission line in the faint, hard states and narrow absorption lines in the bright, soft states of the microquasar GRS 1915+105. ({\textquoteleft}Hard{\textquoteright} and {\textquoteleft}soft{\textquoteright} denote the character of the emitted X-rays.) Because the hard states exhibit prominent radio jets, we argue that the broad emission line arises when the jet illuminates the inner accretion disk. The jet is weak or absent during the soft states, and we show that the absorption lines originate when the powerful radiation field around the black hole drives a hot wind off the accretion disk. Our analysis shows that this wind carries enough mass away from the disk to halt the flow of matter into the radio jet. }},
	doi = {10.1038/nature07680},
	url = {https://www.nature.com/articles/nature07680.pdf},
	author = {{Neilsen}, J. and {Lee}, J.~C.}
}
@article {2009ApJ...701..984X,
	title = {{The Accretion Disk Corona and Disk Atmosphere of 4U 1624-490 as Viewed by the Chandra-High Energy Transmission Grating Spectrometer}},
	journal = {The Astrophysical Journal},
	volume = {701},
	year = {2009},
	note = {n/a},
	month = {aug},
	pages = {984-993},
	abstract = {{We present a detailed spectral study (photoionization modeling and variability) of the {\textquoteright}{\textquoteright}Big Dipper{\textquoteright}{\textquoteright} 4U 1624-490 based on a Chandra-High Energy Transmission Grating Spectrometer (HETGS) observation over the \~{}76 ks binary orbit of 4U 1624-490 . While the continuum spectrum can be modeled using a blackbody plus power law, a slightly better fit is obtained using a single {$\Gamma$} = 2.25 power-law partially (71\%) covered by a local absorber of column density N\_H Local=8.1\_$\{$-0.6$\}$\^{}$\{$+0.7$\}${\times} 10\^{}$\{$22$\}$ cm\^{}$\{$-2$\}$. The data show a possible quasi-sinusoidal modulation with period 43$^{+13}$ $_{-9}$ ks that might be due to changes in local obscuration. Photoionization modeling with the XSTAR code and variability studies of the observed strong Fe XXV and Fe XXVI absorption lines point to a two-temperature plasma for their origin: a highly ionized component of ionization parameter {$\xi$}$_{hot}$ {\ap} 10$^{4.3}$ erg cm s$^{-1}$ (T \~{} 3.0 {\times} 10$^{6}$ K) associated with an extended accretion disk corona of radius R \~{} 3 {\times} 10$^{10}$ cm, and a less-ionized more variable component of {$\xi$} {\ap} 10$^{3.4}$ erg cm s$^{-1}$ (T \~{} 1.0 {\times} 10$^{6}$ K) and {$\xi$} {\ap} 10\^{}$\{$3.1$\}$ erg cm s\^{}$\{$-1$\}$ (T \~{} 0.9 {\times} 10$^{6}$ K) coincident with the accretion disk rim. We use this, with the observed Fe XXV and Fe XXVI absorption line variations (in wavelength, strength, and width) to construct a viewing geometry that is mapped to changes in plasma conditions over the 4U 1624-490 orbital period. }},
	doi = {10.1088/0004-637X/701/2/984},
	author = {{Xiang}, J. and {Lee}, J.~C. and {Nowak}, M.~A. and {Wilms}, J. and {Schulz}, N.~S.}
}
@article {2009ApJ...696..182N,
	title = {{Spectroscopic Signatures of the Superorbital Period in the Neutron Star Binary LMC X-4}},
	journal = {\apj},
	volume = {696},
	year = {2009},
	note = {n/a},
	month = {may},
	pages = {182-191},
	abstract = {{We present the first high-resolution X-ray study of emission line variability with superorbital phase in the neutron star binary LMC X-4. Our analysis provides new evidence from X-ray spectroscopy confirming accretion disk precession as the origin of the superorbital period. The spectra, obtained with the Chandra High-Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer, contain a number of emission features, including lines from hydrogen-like and helium-like species of N, O, Ne, and Fe, a narrow O VII radiative recombination continua (RRCs), and fluorescent emission from cold Fe. We use the narrow RRC and the He{$\alpha$} triplets to constrain the temperature and density of the (photoionized) gas. By comparing spectra from different superorbital phases, we attempt to isolate the contributions to line emission from the accretion disk and the stellar wind. There is also evidence for highly ionized iron redshifted and blueshifted by \~{}25,000 km s$^{-1}$. We argue that this emission originates in the inner accretion disk and show that the emission line properties in LMC X-4 are natural consequences of accretion disk precession. }
},
	doi = {10.1088/0004-637X/696/1/182},
	author = {{Neilsen}, J. and {Lee}, J.~C. and {Nowak}, M.~A. and {Dennerl}, K. and {Vrtilek}, S.~D.}
}
@article {2009ApJ...702..970L,
	title = {{Condensed Matter Astrophysics: A Prescription for Determining the Species-specific Composition and Quantity of Interstellar Dust Using X-rays}},
	journal = {\apj},
	volume = {702},
	year = {2009},
	note = {n/a},
	month = {sep},
	pages = {970-979},
	abstract = {{We present a new technique for determining the quantity and composition of dust in astrophysical environments using {\l}t}6 keV X-rays. We argue that high-resolution X-ray spectra as enabled by the Chandra and XMM-Newton gratings should be considered a powerful and viable new resource for delving into a relatively unexplored regime for directly determining dust properties: composition, quantity, and distribution. We present initial cross section measurements of astrophysically likely iron-based dust candidates taken at the Lawrence Berkeley National Laboratory Advanced Light Source synchrotron beamline, as an illustrative tool for the formulation of our technique for determining the quantity and composition of interstellar dust with X-rays. (Cross sections for the materials presented here will be made available for astrophysical modeling in the near future.) Focused at the 700 eV Fe L$_{ III }$ and L$_{ II }$ photoelectric edges, we discuss a technique for modeling dust properties in the soft X-rays using L-edge data to complement K-edge X-ray absorption fine structure analysis techniques discussed by Lee {\amp} Ravel. The paper is intended to be a techniques paper of interest and useful to both condensed matter experimentalists and astrophysicists. For the experimentalists, we offer a new prescription for normalizing relatively low signal-to-noise ratio L-edge cross section measurements. For astrophysics interests, we discuss the use of X-ray absorption spectra for determining dust composition in cold and ionized astrophysical environments and a new method for determining species-specific gas and dust ratios. Possible astrophysical applications of interest, including relevance to Sagittarius A*, are offered. Prospects for improving on this work in future X-ray missions with higher throughput and spectral resolution are also presented in the context of spectral resolution goals for gratings and calorimeters, for proposed and planned missions such as Astro-H and the International X-ray Observatory. }
},
	doi = {10.1088/0004-637X/702/2/970},
	author = {{Lee}, J.~C. and {Xiang}, J. and {Ravel}, B. and {Kortright}, J. and {Flanagan}, K.}
}
@conference {2009astro2010S.178L,
	title = {{Solid State Astrophysics: Probing Interstellar Dust and Gas Properties with X-rays}},
	booktitle = {astro2010: The Astronomy and Astrophysics Decadal Survey},
	series = {ArXiv Astrophysics e-prints},
	volume = {2010},
	year = {2009},
	note = {n/a},
	pages = {178},
	abstract = {{The abundances of gas and dust (solids and complex molecules) in the interstellar medium (ISM) as well as their composition and structures impact practically all of astrophysics. Fundamental processes from star formation to stellar winds to galaxy formation all scale with the number of metals. However, significant uncertainties remain in both absolute and relative abundances, as well as how these vary with environment, e.g., stellar photospheres versus the interstellar medium (ISM). While UV, optical, IR, and radio studies have considerably advanced our understanding of ISM gas and dust, they cannot provide uniform results over the entire range of column densities needed. In contrast, X-rays will penetrate gas and dust in the cold (3K) to hot (100,000,000K) Universe over a wide range of column densities (log NH=20-24 cm\^{}-2), imprinting spectral signatures that reflect the individual atoms which make up the gas, molecule or solid. *X-rays therefore are a powerful and viable resource for delving into a relatively unexplored regime for determining gas abundances and dust properties such as composition, charge state, structure, and quantity via absorption studies, and distribution via scattering halos.* }
},
	author = {{Lee}, J.~C. and {Smith}, R.~K. and {Canizares}, C.~R. and {Costantini}, E. and {de Vries}, C. and {Drake}, J. and {Dwek}, E. and {Edgar}, R. and {Juett}, A.~M. and {Li}, A. and {Lisse}, C. and {Paerels}, F. and {Patnaude}, D. and {Ravel}, B. and {Schulz}, N.~S. and {Snow}, T.~P. and {Valencic}, L.~A. and {Wilms}, J. and {Xiang}, J.}
}
@article {2009ApJ...702..970L,
	title = {{Condensed Matter Astrophysics: A Prescription for Determining the Species-specific Composition and Quantity of Interstellar Dust Using X-rays}},
	journal = {\apj},
	volume = {702},
	year = {2009},
	note = {n/a},
	month = {sep},
	pages = {970-979},
	abstract = {{We present a new technique for determining the quantity and composition of dust in astrophysical environments using {\l}t}6 keV X-rays. We argue that high-resolution X-ray spectra as enabled by the Chandra and XMM-Newton gratings should be considered a powerful and viable new resource for delving into a relatively unexplored regime for directly determining dust properties: composition, quantity, and distribution. We present initial cross section measurements of astrophysically likely iron-based dust candidates taken at the Lawrence Berkeley National Laboratory Advanced Light Source synchrotron beamline, as an illustrative tool for the formulation of our technique for determining the quantity and composition of interstellar dust with X-rays. (Cross sections for the materials presented here will be made available for astrophysical modeling in the near future.) Focused at the 700 eV Fe L$_{ III }$ and L$_{ II }$ photoelectric edges, we discuss a technique for modeling dust properties in the soft X-rays using L-edge data to complement K-edge X-ray absorption fine structure analysis techniques discussed by Lee {\amp} Ravel. The paper is intended to be a techniques paper of interest and useful to both condensed matter experimentalists and astrophysicists. For the experimentalists, we offer a new prescription for normalizing relatively low signal-to-noise ratio L-edge cross section measurements. For astrophysics interests, we discuss the use of X-ray absorption spectra for determining dust composition in cold and ionized astrophysical environments and a new method for determining species-specific gas and dust ratios. Possible astrophysical applications of interest, including relevance to Sagittarius A*, are offered. Prospects for improving on this work in future X-ray missions with higher throughput and spectral resolution are also presented in the context of spectral resolution goals for gratings and calorimeters, for proposed and planned missions such as Astro-H and the International X-ray Observatory. }
},
	doi = {10.1088/0004-637X/702/2/970},
	author = {{Lee}, J.~C. and {Xiang}, J. and {Ravel}, B. and {Kortright}, J. and {Flanagan}, K.}
}
@article {2008ApJ...675.1057E,
	title = {{A Radio through X-Ray Study of the Jet/Companion-Galaxy Interaction in 3C 321}},
	journal = {\apj},
	volume = {675},
	year = {2008},
	note = {n/a},
	month = {mar},
	pages = {1057-1066},
	abstract = {{We present a multiwavelength study of the nucleus, environment, jets, and hot spots of the nearby FR II radio galaxy 3C 321, using new and archival data from MERLIN, the VLA, Spitzer, HST, and Chandra. An initially collimated radio jet extends northwest from the nucleus of its host galaxy and produces a compact knot of radio emission adjacent (in projection) to a companion galaxy, after which it dramatically flares and bends, extending out in a diffuse structure 35 kpc northwest of the nucleus. We argue that the simplest explanation for the unusual morphology of the jet is that it is undergoing an interaction with the companion galaxy. Given that the northwest hot spot that lies {\gt}\~{}250 kpc from the core shows X-ray emission, which likely indicates in situ high-energy particle acceleration, we argue that the jet-companion interaction is not a steady state situation. Instead, we suggest that the jet has been disrupted on a timescale less than the light-travel time to the end of the lobe, \~{}10$^{6}$ yr, and that the jet flow to this hot spot will only be disrupted for as long as the jet-companion interaction takes place. The host galaxy of 3C 321 and the companion galaxy are in the process of merging, and each hosts a luminous AGN. As this is an unusual situation, we investigate the hypothesis that the interacting jet has driven material on to the companion galaxy, triggering its AGN. Finally, we present detailed radio and X-ray observations of both hot spots, which show that there are multiple emission sites, with spatial offsets between the radio and X-ray emission. }
},
	doi = {10.1086/527410},
	author = {{Evans}, D.~A. and {Fong}, W.-F. and {Hardcastle}, M.~J. and {Kraft}, R.~P. and {Lee}, J.~C. and {Worrall}, D.~M. and {Birkinshaw}, M. and {Croston}, J.~H. and {Muxlow}, T.~W.~B.}
}
@article {2008ApJ...688..844E,
	title = {{XMM-Newton Observations of the Nuclei of the Radio Galaxies 3C 305, DA 240, and 4C 73.08}},
	journal = {\apj},
	volume = {688},
	year = {2008},
	note = {n/a},
	month = {dec},
	pages = {844-851},
	abstract = {{We present new XMM-Newton EPIC observations of the nuclei of the nearby radio galaxies 3C 305, DA 240, and 4C 73.08, and investigate the origin of their nuclear X-ray emission. The nuclei of the three sources appear to have different relative contributions of accretion- and jet-related X-ray emission, as expected based on earlier work. The X-ray spectrum of the FR II narrow-line radio galaxy (NLRG) 4C 73.08 is modeled with the sum of a heavily absorbed power law that we interpret to be associated with a luminous accretion disk and circumnuclear obscuring structure, and an unabsorbed power law that originates in an unresolved jet. This behavior is consistent with other narrow-line radio galaxies. The X-ray emission of the low-excitation FR II radio galaxy DA 240 is best modeled as an unabsorbed power law that we associate with a parsec-scale jet, similar to other low-excitation sources that we have studied previously. However, the X-ray nucleus of the narrow-line radio galaxy 3C 305 shows no evidence for the heavily absorbed X-ray emission that has been found in other NLRGs. It is possible that the nuclear optical spectrum in 3C 305 is intrinsically weak-lined, with the strong emission arising from extended regions that indicate the presence of jet-environment interactions. Our observations of 3C 305 suggest that this source is more closely related to other weak-lined radio galaxies. This ambiguity could extend to other sources currently classified as NLRGs. We also present XMM-Newton and VLA observations of the hot spot of DA 240, arguing that this is another detection of X-ray synchrotron emission from a low-luminosity hot spot. }
},
	doi = {10.1086/592266},
	author = {{Evans}, D.~A. and {Hardcastle}, M.~J. and {Lee}, J.~C. and {Kraft}, R.~P. and {Worrall}, D.~M. and {Birkinshaw}, M. and {Croston}, J.~H.}
}
@article {2007ApJ...655..749G,
	title = {{Line Variability in the High-Resolution X-Ray Spectrum of MCG -6-30-15}},
	journal = {\apj},
	volume = {655},
	year = {2007},
	note = {n/a},
	month = {feb},
	pages = {749-761},
	abstract = {{The recent 540 ks Chandra HETGS spectrum of the well-studied, variable active galactic nucleus (AGN) MCG -6-30-15 shows strong 1s-2p absorption lines from many ions. The spectrum was obtained over a period of about 10 days, and the large number of counts in the spectrum makes it ideal for testing variability on short timescales. We apply quantitative tests for line variability to the 1s-2p absorption lines of H- and He-like Ne, Mg, Si, and S. We find significant correlations and anticorrelations between lines as a function of time, much as we would expect if ionization levels in the absorber were varying. We also find evidence for variation in at least one 1s-2p resonance absorption line as a function of luminosity. We consider several possibilities to explain the line variation. First we consider factors that could change ionization levels in the absorber: radial motion, density variation, luminosity variation, and continuum shape variation. None of these individually can explain the line variation, although we cannot completely constrain continuum shape variation without simultaneous knowledge of the ultraviolet (UV) continuum. Other factors, considered individually, are also unable to explain all the variation: multiple changing continuum components, variable obscuration, and changes in velocity dispersion. Changes in line emission are an unlikely cause of significant variation in absorption-line measurements, but we are unable to fully constrain them. Variability could be due to a changing line of sight through a structured absorber. Modeling such scenarios should produce useful constraints on continuum emission mechanisms and absorber structure. }
},
	doi = {10.1086/510441},
	author = {{Gibson}, R.~R. and {Canizares}, C.~R. and {Marshall}, H.~L. and {Young}, A.~J. and {Lee}, J.~C.}
}
@article {2007ApJ...660.1309X,
	title = {{Using the X-Ray Dust Scattering Halo of 4U 1624-490 to Determine Distance and Dust Distributions}},
	journal = {\apj},
	volume = {660},
	year = {2007},
	note = {n/a},
	month = {may},
	pages = {1309-1318},
	abstract = {{We present X-ray dust scattering halo results based on our 76 ks Chandra ACIS-S/HETGS observation of the LMXB dipping source 4U 1624-490. Through analysis of the halo light curves with 2-6 keV spectra over the persistent and dipping periods, we estimate a geometric distance of \~{}15 kpc to 4U 1624-490. We also fit halo radial profiles with different ISM dust grain models to assess the location, uniformity, and density of the halo. Our analysis shows that the dust spatial distribution is not uniform along the line of sight; rather, it is consistent with the spiral arm structure mapped in H II. The large difference between the absorption hydrogen column (N$^{abs}$$_{H}$\~{}8{\times}10$^{22}$ cm$^{-2}$; probes all gas along the line of sight) derived from broadband spectral fitting and the scattering hydrogen column (N$^{sca}$$_{H}$\~{}4{\times}10$^{22}$ cm$^{-2}$; probes only Galactic gas) derived from our studies of the 4U 1624-490 X-ray halo suggests that a large fraction of the column is local to the X-ray binary. We also present (and apply) a new method for assessing the Chandra point-spread function at large ({\gt}50{\textquoteright}{\textquoteright}) angles, through use of the time delays from the observed dips. }
},
	doi = {10.1086/513308},
	author = {{Xiang}, J. and {Lee}, J.~C. and {Nowak}, M.~A.}
}
@article {2007ApJ...671.1345E,
	title = {{Probing Unification with Chandra HETGS and XMM-Newton EPIC and RGS Spectroscopy of the Narrow Emission Line Galaxy NGC 2110}},
	journal = {\apj},
	volume = {671},
	year = {2007},
	note = {n/a},
	month = {dec},
	pages = {1345-1354},
	abstract = {{We present results from Chandra HETGS (250 ks over two epochs) and XMM-Newton EPIC and RGS (60 ks) observations of NGC 2110, which has been historically classified as a narrow emission line galaxy. Our results support the interpretation that the source is a Seyfert 2 viewed through a patchy absorber. The nuclear X-ray spectrum of the source is best described by a power law of photon index {$\Gamma$}\~{}1.7, modified by absorption from multiple layers of neutral material at a large distance from the central supermassive black hole. We report the strong detections of Fe K{$\alpha$} and Si K{$\alpha$} lines, which are marginally resolved with the Chandra HETGS, and we constrain the emission radius of the fluorescing material to {\gt}\~{}1 pc. There is some evidence for modest additional broadening at the base of the narrow Fe K{$\alpha$} core with a velocity \~{}4500 km s$^{-1}$. We find tentative evidence for ionized emission (O VIII Ly{$\alpha$}, an O VIII RRC feature, and possibly a Ne IX forbidden line) in the Chandra MEG and XMM-Newton RGS spectra, which could be associated with the known extended X-ray emission that lies \~{}160 pc from the nucleus. We suggest that the 10$^{23}$ cm$^{-2}$ partially covering absorber originates in broad-line region clouds in the vicinity of the AGN, and that the 3{\times}10$^{22}$ cm$^{-2}$ coverer is likely to have a more distant origin and have a flattened geometry in order to allow the small-scale radio jet to escape. }
},
	doi = {10.1086/523037},
	author = {{Evans}, D.~A. and {Lee}, J.~C. and {Turner}, T.~J. and {Weaver}, K.~A. and {Marshall}, H.~L.}
}
@article {2007ApJ...660.1309X,
	title = {{Using the X-Ray Dust Scattering Halo of 4U 1624-490 to Determine Distance and Dust Distributions}},
	journal = {\apj},
	volume = {660},
	year = {2007},
	note = {n/a},
	pages = {1309-1318},
	abstract = {{We present X-ray dust scattering halo results based on our 76 ks Chandra ACIS-S/HETGS observation of the LMXB dipping source 4U 1624-490. Through analysis of the halo light curves with 2-6 keV spectra over the persistent and dipping periods, we estimate a geometric distance of \~{}15 kpc to 4U 1624-490. We also fit halo radial profiles with different ISM dust grain models to assess the location, uniformity, and density of the halo. Our analysis shows that the dust spatial distribution is not uniform along the line of sight; rather, it is consistent with the spiral arm structure mapped in H II. The large difference between the absorption hydrogen column (N$^{abs}$$_{H}$\~{}8{\times}10$^{22}$ cm$^{-2}$; probes all gas along the line of sight) derived from broadband spectral fitting and the scattering hydrogen column (N$^{sca}$$_{H}$\~{}4{\times}10$^{22}$ cm$^{-2}$; probes only Galactic gas) derived from our studies of the 4U 1624-490 X-ray halo suggests that a large fraction of the column is local to the X-ray binary. We also present (and apply) a new method for assessing the Chandra point-spread function at large ({\gt}50{\textquoteright}{\textquoteright}) angles, through use of the time delays from the observed dips. }
},
	doi = {10.1086/513308},
	author = {{Xiang}, J. and {Lee}, J.~C. and {Nowak}, M.~A.}
}
@conference {2006ESASP.604..475Y,
	title = {{A Chandra HETGS Spectral Study of the Iron K Bandpass in MCG-6-30-15: A Narrow View of the Broad Iron Line}},
	booktitle = {The X-ray Universe 2005},
	series = {ESA Special Publication},
	volume = {604},
	year = {2006},
	note = {n/a},
	month = {jan},
	pages = {475},
	abstract = {n/a},
	author = {{Young}, A.~J. and {Lee}, J.~C. and {Fabian}, A.~C. and {Reynolds}, C.~S. and {Gibson}, R.~R. and {Canizares}, C.~R.},
	editor = {{Wilson}, A.}
}
@article {2006ApJ...653.1121E,
	title = {{The Chandra, Hubble Space Telescope, and VLA View of the Circumnuclear Extended Emission in the Narrow Emission Line Galaxy NGC 2110}},
	journal = {\apj},
	volume = {653},
	year = {2006},
	note = {n/a},
	month = {dec},
	pages = {1121-1128},
	abstract = {{We present results from new Chandra, archival Hubble Space Telescope (HST), and VLA imaging observations of the circumnuclear extended emission in the nearby Type 2 Seyfert galaxy NGC 2110. We find resolved soft-band X-ray emission \~{}4{\textquoteright}{\textquoteright} (\~{}160 pc) north of the nucleus, which is spatially coincident with [O III] emission, but lies just beyond the northern edge of the radio jet in the source. We find that shock heating of multiphase gas clouds can successfully account for this extended emission, although we cannot rule out alternative models, such as the scattering of nuclear radiation by ionized material, or pure photoionization from the nucleus. In addition, we detect kiloparsec-scale (\~{}30{\textquoteright}{\textquoteright}) extended soft-band X-ray emission south of the nucleus. Finally, we compare our results for NGC 2110 with the prototypical type 2 Seyfert galaxy NGC 1068, and suggest that different physical processes could produce extended circumnuclear X-ray emission in Seyfert galaxies. }
},
	doi = {10.1086/508680},
	author = {{Evans}, D.~A. and {Lee}, J.~C. and {Kamenetska}, M. and {Gallagher}, S.~C. and {Kraft}, R.~P. and {Hardcastle}, M.~J. and {Weaver}, K.~A.}
}
@article {2005ApJ...622..970L,
	title = {{Determining the Grain Composition of the Interstellar Medium with High-Resolution X-Ray Spectroscopy}},
	journal = {\apj},
	volume = {622},
	year = {2005},
	note = {n/a},
	pages = {970-976},
	abstract = {{We investigate the ability of high-resolution X-ray spectroscopy to directly probe the grain composition of the interstellar medium. Using iron K-edge experimental data of likely ISM dust candidates taken at the National Synchrotron Light Source at Brookhaven National Laboratory and the Advanced Photon Source at Argonne National Laboratory, we explore the prospects for determining the chemical composition of astrophysical dust and discuss a technique for doing so. Focusing on the capabilities of the Astro-E2 XRS microcalorimeters, we assess the limiting effects of spectral resolution and noise for detecting significant X-ray absorption fine structure signal in astrophysical environments containing dust. We find that given sufficient signal, the resolution of the XRS will allow us to definitively distinguish gas-phase from dust-phase absorption and certain chemical compositions. }
},
	doi = {10.1086/428118},
	author = {{Lee}, J.~C. and {Ravel}, B.}
}
@article {2005ApJ...627...83G,
	title = {{The High-Resolution X-Ray Spectrum of MR 2251-178 Obtained with the Chandra HETGS}},
	journal = {\apj},
	volume = {627},
	year = {2005},
	note = {n/a},
	month = {jul},
	pages = {83-96},
	abstract = {{The QSO MR 2251-178 was observed with the Chandra High Energy Transmission Grating Spectrometer (HETGS) at a 2-10 keV luminosity of 2.41{\times}10$^{44}$ ergs s$^{-1}$ (using H$_{0}$=72 km s$^{-1}$ Mpc$^{-1}$). We observe the source in a relatively low state. The light curve shows no evidence of variability. We present the zero-order image of MR 2251-178 and compare it to previous observations. We find evidence of a highly ionized, high-velocity outflow, which we detect in a resolved Fe XXVI Ly{$\alpha$} absorption line. The outflow appears to have a large mass and kinetic energy flux compared to the estimated nuclear accretion rate and luminosity. We examine the possibility that other absorption features in the spectrum are associated with the high-velocity outflow. We detect a narrow Fe K{$\alpha$} line and resolved forbidden line emission from Ne IX and O VII. Modeling the emitting material enables us to constrain its properties and conclude that it is not along our line of sight. }
},
	doi = {10.1086/430199},
	author = {{Gibson}, R.~R. and {Marshall}, H.~L. and {Canizares}, C.~R. and {Lee}, J.~C.}
}
@article {2005ApJ...634..193S,
	title = {{Intrinsic Absorption in the Spectrum of NGC 7469: Simultaneous Chandra, FUSE, and STIS Observations}},
	journal = {\apj},
	volume = {634},
	year = {2005},
	note = {n/a},
	month = {nov},
	pages = {193-209},
	abstract = {{We present simultaneous X-ray, far-ultraviolet, and near-ultraviolet spectra of the Seyfert 1 galaxy NGC 7469 obtained with the Chandra X-Ray Observatory, the Far Ultraviolet Spectroscopic Explorer, and the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Previous nonsimultaneous observations of this galaxy found two distinct UV absorption components, at -560 and -1900 km s$^{-1}$, with the former as the likely counterpart of the X-ray absorber. We confirm these two absorption components in our new UV observations, in which we detect prominent O VI, Ly{$\alpha$}, N V, and C IV absorption. In our Chandra spectrum we detect O VIII emission, but no significant O VIII or O VII absorption. We also detect a prominent Fe K{$\alpha$} emission line in the Chandra spectrum, as well as absorption due to hydrogen-like and helium-like neon, magnesium, and silicon at velocities consistent with the -560 km s$^{-1}$ UV absorber. The FUSE and STIS data reveal that the H I and C IV column densities in this UV- and X-ray-absorbing component have increased over time, as the UV continuum flux decreased. We use measured H I, N V, C IV, and O VI column densities to model the photoionization state of both absorbers self-consistently. We confirm the general physical picture of the outflow in which the low-velocity component is a highly ionized, high-density absorber with a total column density of 10$^{20}$ cm$^{-2}$, located near the broad emission-line region, although due to measurable columns of N V and C IV, we assign it a somewhat smaller ionization parameter than found previously, U\~{}1. The high-velocity UV component is of lower densit
},
	doi = {10.1086/496911},
	author = {{Scott}, J.~E. and {Kriss}, G.~A. and {Lee}, J.~C. and {Quijano}, J.~K. and {Brotherton}, M. and {Canizares}, C.~R. and {Green}, R.~F. and {Hutchings}, J. and {Kaiser}, M.~E. and {Marshall}, H. and {Oegerle}, W. and {Ogle}, P. and {Zheng}, W.}
}
@article {2005ApJ...622..970L,
	title = {{Determining the Grain Composition of the Interstellar Medium with High-Resolution X-Ray Spectroscopy}},
	journal = {\apj},
	volume = {622},
	year = {2005},
	note = {n/a},
	pages = {970-976},
	abstract = {{We investigate the ability of high-resolution X-ray spectroscopy to directly probe the grain composition of the interstellar medium. Using iron K-edge experimental data of likely ISM dust candidates taken at the National Synchrotron Light Source at Brookhaven National Laboratory and the Advanced Photon Source at Argonne National Laboratory, we explore the prospects for determining the chemical composition of astrophysical dust and discuss a technique for doing so. Focusing on the capabilities of the Astro-E2 XRS microcalorimeters, we assess the limiting effects of spectral resolution and noise for detecting significant X-ray absorption fine structure signal in astrophysical environments containing dust. We find that given sufficient signal, the resolution of the XRS will allow us to definitively distinguish gas-phase from dust-phase absorption and certain chemical compositions. }
},
	doi = {10.1086/428118},
	author = {{Lee}, J.~C. and {Ravel}, B.}
}
@article {2004MNRAS.347..411I,
	title = {{The hard X-ray spectrum of the Seyfert galaxy IRAS 18325-5926: reflection from an ionized disc and variable iron K emission}},
	journal = {\mnras},
	volume = {347},
	year = {2004},
	note = {n/a},
	month = {jan},
	pages = {411-420},
	abstract = {{We report our analysis of the X-ray spectra of the Seyfert galaxy IRAS 18325-5926 (= Fairall 49) obtained from various X-ray observatories prior to XMM-Newton, including new results from two RXTE and one BeppoSAX observations. A relatively steep continuum slope ({$\Gamma$}\~{}= 2.2) in the 2-15 keV band is confirmed. The continuum spectrum observed with the BeppoSAX PDS shows a possible roll-over at energies above 30 keV, indicating a Comptonizing corona cooler than in other Seyfert nuclei. The X-ray spectrum above 2 keV is best explained with a model including reflection from a highly ionized disc with significant relativistic blurring. The iron K{$\alpha$} emission feature is then mainly due to FeXXV. The seven recent observations show that the iron K emission flux appears to follow the continuum between the observations separated by a few months to years, although some exceptions suggest that the linestrength may be determined in a more complex way. }
},
	doi = {10.1111/j.1365-2966.2004.07206.x},
	author = {{Iwasawa}, K. and {Lee}, J.~C. and {Young}, A.~J. and {Reynolds}, C.~S. and {Fabian}, A.~C.}
}
@article {2004ApJS..152....1S,
	title = {{Intrinsic Absorption in the Spectrum of Markarian 279: Simultaneous Chandra, FUSE, and STIS Observations}},
	journal = {\apjs},
	volume = {152},
	year = {2004},
	note = {n/a},
	month = {may},
	pages = {1-27},
	abstract = {{We present a study of the intrinsic X-ray and far-ultraviolet absorption in the Seyfert 1.5 galaxy Markarian 279 using simultaneous observations from the Chandra X-ray Observatory, the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, and the Far Ultraviolet Spectroscopic Explorer (FUSE). We also present FUSE observations made at three additional epochs. We detect the Fe K{$\alpha$} emission line in the Chandra spectrum, and its flux is consistent with the low X-ray continuum flux level of Mrk 279 at the time of the observation. Because of low signal-to-noise ratios (S/N) in the Chandra spectrum, no O VII or O VIII absorption features are observable in the Chandra data, but the UV spectra reveal strong and complex absorption from H I and high-ionization species such as O VI, N V, and C IV, as well as from low-ionization species such as C III, N III, C II, and N II in some velocity components. The far-UV spectral coverage of the FUSE data provides information on high-order Lyman series absorption, which we use to calculate the optical depths and line and continuum covering fractions in the intrinsic H I absorbing gas in a self-consistent fashion. The UV continuum flux of Mrk 279 decreases by a factor of \~{}7.5 over the time spanning these observations and we discuss the implications of the response of the absorption features to this change. From arguments based on the velocities, profile shapes, covering fractions and variability of the UV absorption, we conclude that some of the absorption components, particularly those showing prominent low-ionization lines, are likely associated with the host galaxy of Mrk 279, and possibly with its interaction with a close companion galaxy, while the remainder arises in a nuclear outflow. }
},
	doi = {10.1086/382748},
	author = {{Scott}, J.~E. and {Kriss}, G.~A. and {Lee}, J.~C. and {Arav}, N. and {Ogle}, P. and {Roraback}, K. and {Weaver}, K. and {Alexander}, T. and {Brotherton}, M. and {Green}, R.~F. and {Hutchings}, J. and {Kaiser}, M.~E. and {Marshall}, H. and {Oegerle}, W. and {Zheng}, W.}
}
@article {2004NuPhS.132..135T,
	title = {{A softer look at MCG-6-30-15 with XMM-Newton}},
	journal = {Nuclear Physics B Proceedings Supplements},
	volume = {132},
	year = {2004},
	note = {n/a},
	pages = {135-140},
	abstract = {{We summarise the initial results from an analysis of a 320 ks observation of the Seyfert 1 galaxy MCG-6-30-15 with the Reflection Grating Spectrometer on-board XMM-Newton. }
},
	doi = {10.1016/j.nuclphysbps.2004.04.017},
	author = {{Turner}, A.~K. and {Fabian}, A.~C. and {Vaughan}, S. and {Lee}, J.~C.}
}
@article {2004MNRAS.353..319T,
	title = {{The soft X-ray absorption lines of the Seyfert 1 galaxy MCG-6-30-15}},
	journal = {\mnras},
	volume = {353},
	year = {2004},
	note = {n/a},
	month = {sep},
	pages = {319-328},
	abstract = {{The absorption lines in the soft X-ray spectrum of MCG-6-30-15 are studied using the reflection grating spectrometer data from the 2001 XMM-Newton 320-ks observation. A line search of the full time-averaged spectrum reveals 51 absorption lines and one emission line. The equivalent widths of the lines are measured and the majority of the lines identified. We find lines produced by a broad range of charge states for several elements, including almost all the charge states of oxygen and iron, suggesting a broad range of ionization parameters is present in the warm absorber. The equivalent widths of the lines are broadly consistent with the best-fitting warm absorber models from Turner et al. The equivalent widths of the absorption lines allow confidence limits on the column density of the species to be determined. For OVII, a column density of 10$^{18.36}$-10$^{18.86}$ cm$^{-2}$ is found. This column density of OVII, when combined with the inferred FeI absorption, is sufficient to explain the drop in flux at 0.7 keV as being due to absorption from the warm absorber. Fitting OI K-edge absorption to the spectrum reveals a column of 10$^{17.51}$-10$^{17.67}$ cm$^{-2}$ of OI, suggesting an Fe:O ratio of \~{}1:2, consistent with the neutral iron being in the form of iron oxide dust. Variability is seen in a few absorption lines, but the majority of the absorption features, including the prominent absorption edges, stay constant throughout the observation despite variability in the continuum flux. }
},
	doi = {10.1111/j.1365-2966.2004.08075.x},
	author = {{Turner}, A.~K. and {Fabian}, A.~C. and {Lee}, J.~C. and {Vaughan}, S.}
}
@article {2003A\&A...402..849O,
	title = {{Testing the Seyfert unification theory: Chandra HETGS observations of NGC 1068}},
	journal = {\aap},
	volume = {402},
	year = {2003},
	note = {n/a},
	month = {may},
	pages = {849-864},
	abstract = {{We present spatially resolved Chandra HETGS observations of the Seyfert 2 galaxy NGC 1068. X-ray imaging and high resolution spectroscopy are used to test the Seyfert unification theory. Fe Kalpha emission is concentrated in the nuclear region, as are neutral and ionized continuum reflection. This is consistent with reprocessing of emission from a luminous, hidden X-ray source by the obscuring molecular torus and X-ray narrow-line region (NLR). We detect extended hard X-ray emission surrounding the X-ray peak in the nuclear region, which may come from the outer portion of the torus. Detailed modeling of the spectrum of the X-ray NLR confirms that it is excited by photoionization and photoexcitation from the hidden X-ray source. K-shell emission lines from a large range of ionization states of H-like and He-like N, O, Ne, Mg, Al, Si, S, and Fe Xvii-XXIV L-shell emission lines are modeled. The emission measure distribution indicates roughly equal masses at all observed ionization levels in the range log xi = 1-3. We separately analyze the spectrum of an off-nuclear cloud. We find that it has a lower column density than the nuclear region, and is also photoionized. The nuclear X-ray NLR column density, optical depth, outflow velocity, and electron temperature are all consistent with values predicted by optical spectropolarimetry for the region which provides a scattered view of the hidden Seyfert 1 nucleus. }
},
	doi = {10.1051/0004-6361:20021647},
	author = {{Ogle}, P.~M. and {Brookings}, T. and {Canizares}, C.~R. and {Lee}, J.~C. and {Marshall}, H.~L.}
}
@article {2002ApJ...564L..21S,
	title = {{The Ionized Stellar Wind in Vela X-1 during Eclipse}},
	journal = {\apjl},
	volume = {564},
	year = {2002},
	note = {n/a},
	month = {jan},
	pages = {L21-L25},
	abstract = {{We present a first analysis of a high-resolution X-ray spectrum of the ionized stellar wind of Vela X-1 during eclipse. The data were obtained with the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory. The spectrum is resolved into emission lines with fluxes between 0.02 and 1.04{\times}10$^{-4}$ photons cm$^{-2}$ s$^{-1}$. We identify lines from a variety of charge states, including fluorescent lines from cold material and a warm photoionized wind. We can exclude signatures from collisionally ionized plasmas. For the first time, we identify fluorescent lines from L-shell ions from lower Z elements. We also detect radiative recombination continua from a kT=10 eV (1.2{\times}10$^{5}$ K) photoionized optically thin gas. The fluorescent line fluxes imly the existence of optically thick and clumped matter within or outside the warm photoionized plasma. }
},
	doi = {10.1086/338862},
	author = {{Schulz}, N.~S. and {Canizares}, C.~R. and {Lee}, J.~C. and {Sako}, M.}
}
@article {2002ApJ...565.1141S,
	title = {{The First High-Resolution X-Ray Spectrum of Cygnus X-1: Soft X-Ray Ionization and Absorption}},
	journal = {\apj},
	volume = {565},
	year = {2002},
	note = {n/a},
	month = {feb},
	pages = {1141-1149},
	abstract = {{We observed the black hole candidate Cyg X-1 for 15 ks with the High-Energy Transmission Grating Spectrometer aboard the Chandra X-Ray Observatory. The source was observed during a period of intense flaring activity, so it was about a factor of 2.5 brighter than usual, with a 0.5-10 keV (1-24 {\AA}) luminosity of 1.6{\times}10$^{37}$ ergs s$^{-1}$ (at a distance of 2.5 kpc). The spectrum of the source shows prominent absorption edges, some of which have a complicated substructure. We use the most recent results from laboratory measurements and calculations to model the observed substructure of the edges. From the model, we derive a total absorption column of (6.21+/-0.22){\times}10$^{21}$ cm$^{-2}$. Furthermore, the results indicate that there are \~{}10\%-25\% abundance variations relative to solar values for neon, oxygen, and iron. The X-ray continuum is well described by a two-component model that is often adopted for black hole candidates: a soft multicolor disk component (with kT=203 eV) and a hard power-law component (with a photon index of \~{}2). Comparing the fit results to those of the hard and soft states, we conclude that the source was in a transitional state. Finally, the spectrum also shows the presence of faint emission lines, which could be attributed to highly ionized species. }
},
	doi = {10.1086/324482},
	author = {{Schulz}, N.~S. and {Cui}, W. and {Canizares}, C.~R. and {Marshall}, H.~L. and {Lee}, J.~C. and {Miller}, J.~M. and {Lewin}, W.~H.~G.}
}
@article {2002ApJ...567.1102L,
	title = {{High-Resolution Chandra HETGS and Rossi X-Ray Timing Explorer Observations of GRS 1915+105: A Hot Disk Atmosphere and Cold Gas Enriched in Iron and Silicon}},
	journal = {\apj},
	volume = {567},
	year = {2002},
	note = {n/a},
	month = {mar},
	pages = {1102-1111},
	abstract = {{The time-averaged 30 ks Chandra AO1 High Energy Transmission Grating Spectrometer observation of the microquasar GRS 1915+105 in the low hard state reveals for the first time in this source neutral K absorption edges from iron, silicon, magnesium, and sulphur. Ionized resonance (r) absorption from H- and He-like species of Fe (XXV, XXVI) and possibly Ca XX are also seen as well as possible emission from neutral Fe K{$\alpha$} and ionized Fe XXV (forbidden or the resonance emission component of a P Cygni profile). We report the tentative detection of the first astrophysical signature of X-ray absorption fine structure in the photoelectric edge of Si (and possibly Fe and Mg) attributed to material in grains. The large column densities measured from the neutral edges reveal anomalous Si and Fe abundances and illustrate the importance of high-resolution X-ray measurements for assessing material that surrounds bright X-ray sources, especially if depletion onto grains plays a prominent role. Scenarios for which the anomalous abundances can be attributed to surrounding cold material associated with GRS 1915+105 and/or for which the enrichment may signify either a highly unusual supernova/hypernova or external supernova activity local to the binary are discussed. We attribute the ionized features to a hot disk, disk wind, or corona environment. Based on H- and He-like Fe (XXV, XXVI), we estimate constraints on the ionization parameter (log{$\xi$}{\gt}\~{}4.15), temperature (T{\gt}2.4{\times}10$^{6}$ K), and hydrogen equivalent number density (n{\gt}\~{}10$^{12}$ cm$^{-3}$) for this region. Variability studies with the simultaneous RXTE data show that the light-curve count rate tracks the changes in the disk blackbody as well as the power-law flux, with the most significant variations observed in the former. The Chandra data show spectral changes that also track the behavior of the light curve and may point to changes in both the ionizing flux and density of the absorber. A 3.69 Hz quasi-periodic oscillation and weak first harmonic are seen in the RXTE data. }
},
	doi = {10.1086/338588},
	author = {{Lee}, J.~C. and {Reynolds}, C.~S. and {Remillard}, R. and {Schulz}, N.~S. and {Blackman}, E.~G. and {Fabian}, A.~C.}
}
@article {2002ApJ...570L..47L,
	title = {{The Shape of the Relativistic Iron K{$\alpha$} Line from MCG -6-30-15 Measured with the Chandra High Energy Transmission Grating Spectrometer and the Rossi X-Ray Timing Explorer}},
	journal = {\apjl},
	volume = {570},
	year = {2002},
	note = {n/a},
	month = {may},
	pages = {L47-L50},
	abstract = {{We confirm the detection of the relativistically broadened iron K{$\alpha$} emission at 6.4 keV with simultaneous Chandra High Energy Transmission Grating Spectrometer (HETGS) and Rossi X-Ray Timing Explorer Proportional Counter Array observations. Heavily binned HETGS data show a disk line profile with parameters very similar to those previously seen by ASCA. We observe a resolved narrow component with a velocity width of \~{}4700 km s$^{-1}$ (FWHM\~{}11,000 km s$^{-1}$) that is most prominent and is narrower (FWHM\~{}3600 km s$^{-1}$) when the continuum flux is high. It is plausibly just the blue wing of the broad line. We obtain a stringent limit on the equivalent width of an intrinsically narrow line in the source of 16 eV, indicating little or no contribution due to fluorescence from distant material, such as the molecular torus. Variability studies of the narrow component show a constant iron line flux and variable width indicating the line may be originating from different kinematic regions of the disk. }
},
	doi = {10.1086/340992},
	author = {{Lee}, J.~C. and {Iwasawa}, K. and {Houck}, J.~C. and {Fabian}, A.~C. and {Marshall}, H.~L. and {Canizares}, C.~R.}
}
@article {2002ApJ...572L.127F,
	title = {{Chandra Detection of O VIII Ly{$\alpha$} Absorption from an Overdense Region in the Intergalactic Medium}},
	journal = {\apjl},
	volume = {572},
	year = {2002},
	note = {n/a},
	month = {jun},
	pages = {L127-L130},
	abstract = {{We report the first detection of an O VIII Ly{$\alpha$} absorption line associated with an overdense region in the intergalactic medium along the sight line toward PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer. The absorption line is detected at the 4.5 {$\sigma$} level with cz\~{}16,600 km s$^{-1}$. At the same velocity, Shull et al. detected a small group of spiral galaxies (with an overdensity of {$δ$}$_{gal}$\~{}100) and low-metallicity H I Ly{$\alpha$} clouds. We constrain the intragroup gas that gives rise to the O VIII Ly{$\alpha$} line to a baryon density in the range 1.0{\times}10$^{-5}$ cm$^{-3}${\l}t}n$_{b}${\l}t}7.5{\times}10$^{-5}$ cm$^{-3}$ (50{\l}t}{$δ$}$_{b}${\l}t}350) and a temperature of (4-5){\times}10$^{6}$ K, assuming 0.1 Z$_{solar}$. These estimates are in accordance with those of the warm/hot intergalactic medium (WHIM) that are predicted from hydrodynamic simulations. Extrapolating from this single detection implies that a large fraction of the {\textquoteleft}{\textquoteleft}missing baryons{\textquoteright}{\textquoteright} (\~{}10\%, or \~{}30\%-40\% of the WHIM) are probed by the O VIII absorber. }
},
	doi = {10.1086/341665},
	author = {{Fang}, T. and {Marshall}, H.~L. and {Lee}, J.~C. and {Davis}, D.~S. and {Canizares}, C.~R.}
}
@article {2002ApJ...573..789C,
	title = {{The X-Ray Position and Infrared Counterpart of the Eclipsing X-Ray Pulsar OAO 1657-415}},
	journal = {\apj},
	volume = {573},
	year = {2002},
	note = {n/a},
	month = {jul},
	pages = {789-793},
	abstract = {{We have measured the precise position of the 38 s eclipsing X-ray pulsar OAO 1657-415 with the Chandra X-Ray Observatory: {$\alpha$}(J2000)=17$^{h}$00$^{m}$48.90$^{s}$, {$δ$}(J2000)=-41$^{deg}$39$^{{\textquoteright}}$21.6{\textquoteright}
},
	doi = {10.1086/340746},
	author = {{Chakrabarty}, D. and {Wang}, Z. and {Juett}, A.~M. and {Lee}, J.~C. and {Roche}, P.}
}
@article {2002ApJ...577..120P,
	title = {{The Distant Type Ia Supernova Rate}},
	journal = {\apj},
	volume = {577},
	year = {2002},
	note = {n/a},
	month = {sep},
	pages = {120-132},
	abstract = {{We present a measurement of the rate of distant Type Ia supernovae derived using four large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 deg$^{2}$, 38 supernovae were detected at redshifts 0.25-0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean redshift z\~{}=0.55 of 1.53$^{+0.28}$$_{-0.25}$$^{+0.32}$$_{- 0.31}${\times}10$^{-4}$ h$^{3}$ Mpc$^{-3}$ yr$^{-1}$ or 0.58$^{+0.10}$$_{-0.09}$$^{+0.10}$$_{-0.09}$ h$^{2}$ SNu (1SNu=1 supernova per century per 10$^{10}$ L$_{Bsolar}$), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models. }
},
	doi = {10.1086/342129},
	author = {{Pain}, R. and {Fabbro}, S. and {Sullivan}, M. and {Ellis}, R.~S. and {Aldering}, G. and {Astier}, P. and {Deustua}, S.~E. and {Fruchter}, A.~S. and {Goldhaber}, G. and {Goobar}, A. and {Groom}, D.~E. and {Hardin}, D. and {Hook}, I.~M. and {Howell}, D.~A. and {Irwin}, M.~J. and {Kim}, A.~G. and {Kim}, M.~Y. and {Knop}, R.~A. and {Lee}, J.~C. and {Lidman}, C. and {McMahon}, R.~G. and {Nugent}, P.~E. and {Panagia}, N. and {Pennypacker}, C.~R. and {Perlmutter}, S. and {Ruiz-Lapuente}, P. and {Schahmaneche}, K. and {Schaefer}, B. and {Walton}, N.~A.}
}
@article {2002MNRAS.335L...1F,
	title = {{A long hard look at MCG-6-30-15 with XMM-Newton}},
	journal = {\mnras},
	volume = {335},
	year = {2002},
	note = {n/a},
	month = {sep},
	pages = {L1-L5},
	abstract = {{We present the first results from a 325-ks observation of the Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and BeppoSAX. The strong, broad, skewed iron line is clearly detected and is well characterized by a steep emissivity profile within 6r$_{g}$ (i.e. 6GM/c$^{2}$) and a flatter profile beyond. The inner radius of the emission appears to lie at about 2r$_{g}$, consistent with results reported from both an earlier XMM-Newton observation of MCG-6-30-15 by Wilms et al. and part of an ASCA observation by Iwasawa et al. when the source was in a lower flux state. The radius and steep emissivity profile do depend however on an assumed incident power-law continuum and a lack of complex absorption above 2.5 keV. The blue wing of the line profile is indented, either by absorption at about 6.7 keV or by a hydrogenic iron emission line. The broad iron line flux does not follow the continuum variations in a simple manner. }
},
	doi = {10.1046/j.1365-8711.2002.05740.x},
	author = {{Fabian}, A.~C. and {Vaughan}, S. and {Nandra}, K. and {Iwasawa}, K. and {Ballantyne}, D.~R. and {Lee}, J.~C. and {de Rosa}, A. and {Turner}, A. and {Young}, A.~J.}
}
@conference {2001ppu..conf...47G,
	title = {{The Acceleration of the Universe:. Measurements of Cosmological Parameters from Type Ia Supernovae}},
	booktitle = {Particle Physics and the Universe},
	year = {2001},
	note = {n/a},
	month = {mar},
	pages = {47-58},
	abstract = {{The fate of the Universe, infinite expansion or a {\textquoteright}{\textquoteright}big crunch{\textquoteright}{\textquoteright}, can be determined by measuring the redshifts and brightness of very distant supernovae. These provide a record of changes in the expansion rate of the Universe over the past several billion years. The mass density, {${\O}mega$}$_{M}$, and cosmological-constant energy density, {${\O}mega$}$_{Λ}$, are measured from a data-set consisting of 42 high-redshift Type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fit jointly with a set of supernovae from the Cal{\'a}n/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. We find {${\O}mega$} $_{M}$ flat = 0.28$_{-0.08}$$^{+0.09}$ (1{$\sigma$} $\backslash$ statistical)$_{-0.04}$$^{+0.05}$ (identified systematics). The data are strongly inconsistent with a {${\L}ambda$} = 0 flat cosmology, the simplest inflationary universe model. An open, {${\L}ambda$} = 0 cosmology also does not fit the data well: the data indicate that the cosmological constant is non-zero and positive, with a confidence of P({${\L}ambda$} {\gt} 0) = 99\%, including the identified systematic uncertainties. Thus, the Universe is found to be accelerating, i.e., q$_{0}$ = {${\O}mega$}$_{M}$/2 - {${\O}mega$}$_{Λ}$ {\l}t} 0. The best-fit age of the universe relative to the Hubble time is t$_{0}$ flat = 14.9$_{-1.1}$$^{+1.4}$ (0.63/h)$\backslash$ Gyr for a flat cosmology. }
},
	doi = {10.1142/9789812810434_0005},
	author = {{Goobar}, A. and {Perlmutter}, S. and {Aldering}, G. and {Goldhaber}, G. and {Knop}, R.~A. and {Nugent}, P. and {Castro}, P.~G. and {Deustua}, S. and {Fabbro}, S. and {Groom}, D.~E. and {Hook}, I.~M. and {Kim}, A.~G. and {Kim}, M.~Y. and {Lee}, J.~C. and {Nunes}, N.~J. and {Pain}, R. and {Pennypacker}, C.~R. and {Quimby}, R. and {Lidman}, C. and {Ellis}, R.~S. and {Irwin}, M. and {McMahon}, R.~G. and {Ruiz-Lapuente}, P. and {Walton}, N. and {Schaefer}, B. and {Boyle}, B.~J. and {Filippenko}, A.~V. and {Matheson}, T. and {Fruchter}, A.~S. and {Panagia}, N. and {Newberg}, H.~J.~M. and {Couch}, W.~J.},
	editor = {{Bergstr{\"o}m}, L. and {Fransson}, C. and {Carlson}, P.}
}
@article {2001astro.ph..9389F,
	title = {{A Chandra HETG Observation of the Quasar H 1821+643 and Its Surrounding Cluster}},
	journal = {ArXiv Astrophysics e-prints},
	year = {2001},
	note = {n/a},
	month = {sep},
	abstract = {{We present the high-resolution X-ray spectrum of the low-redshift quasar H 1821+643 and its surrounding hot cluster observed with the Chandra High Energy Transmission Grating Spectrometer (HETGS). An iron emission line attributed to the quasar at \~{}6.43 keV (rest frame) is clearly resolved, with an equivalent width of \~{}100 eV. Although we cannot rule out contributions to the line from a putative torus, the diskline model provides an acceptable fit to this iron line. We also detect a weak emission feature at \~{}6.9 keV (rest frame). We suggest that both lines could originate in an accretion disk comprised of a highly ionized optically thin atmosphere sitting atop a mostly neutral disk. We search for absorption features from a warm/hot component of the intergalactic medium along the \~{}1.5Gpc/h line of sight to the quasar. No absorption features are detected at or above the 3 sigma level while a total of six OVI intervening absorption systems have been detected with HST and FUSE. Based on the lack of OVII and OVIII absorption lines and by assuming collisionally ionization, we constrain the gas temperature of a typical OVI absorber to 10\^{}5 {\l}t} T {\l}t} 10\^{}6 K, which is consistent with the results from hydrodynamic simulations of the intergalactic medium. The zeroth order image reveals the extended emission from the surrounding cluster. We have been able to separate the moderate CCD X-ray spectrum of the surrounding cluster from the central quasar and find that this is a hot cluster with a temperature of \~{}10 keV and a metal abundance of \~{}0.3 Zo. We also independently obtain the redshift of the cluster, which is consistent with the optical results. We estimate that the cluster makes negligible contributions to the 6.9 keV iron K line flux. }
},
	author = {{Fang}, T. and {Davis}, D.~S. and {Lee}, J.~C. and {Marshall}, H.~L. and {Bryan}, G.~L. and {Canizares}, C.~R.}
}
@article {2001ApJ...554L..13L,
	title = {{Revealing the Dusty Warm Absorber in MCG -6-30-15 with the Chandra High-Energy Transmission Grating}},
	journal = {\apjl},
	volume = {554},
	year = {2001},
	note = {n/a},
	month = {jun},
	pages = {L13-L17},
	abstract = {{We present detailed evidence for a warm absorber in the Seyfert 1 galaxy MCG -6-30-15 and dispute earlier claims for relativistic O line emission. The High-Energy Transmission Grating spectra show numerous narrow, unresolved (FWHM{\l}t}\~{}200 km s$^{-1}$) absorption lines from a wide range of ionization states of N, O, Mg, Ne, Si, S, Ar, and Fe. The O VII edge and the 1s$^{2}$-1snp resonance line series to n=9 are clearly detected at rest in the active galactic nucleus frame. We attribute previous reports of an apparently highly redshifted O VII edge to the 1s$^{2}$-1snp (n{\gt}5) O VII resonance lines and a neutral Fe L absorption complex. The shape of the Fe L feature is nearly identical to that seen in the spectra of several X-ray binaries and in laboratory data. The implied dust column density agrees with that obtained from reddening studies and gives the first direct X-ray evidence for dust embedded in a warm absorber. The O VIII resonance lines and the weak edge are also detected, and the spectral rollover below \~{}2 keV is explained by the superposition of numerous absorption lines and edges. We identify, for the first time, a KLL resonance in the O VI photoabsorption cross section, giving a measure of the O VI column density. The O VII (f) emission detected at the systemic velocity implies a covering fraction of \~{}5\% (depending on the observed vs. time-averaged ionizing flux). Our observations show that a dusty warm absorber model is not only adequate to explain all the spectral features {\gt}\~{}0.48 keV ({\l}t}\~{}26 {\AA}) but that the data require it. This contradicts the interpretation of Branduardi-Raymont and coworkers that this spectral region is dominated by highly relativistic line emission from the vicinity of the black hole. }
},
	doi = {10.1086/320912},
	author = {{Lee}, J.~C. and {Ogle}, P.~M. and {Canizares}, C.~R. and {Marshall}, H.~L. and {Schulz}, N.~S. and {Morales}, R. and {Fabian}, A.~C. and {Iwasawa}, K.}
}
@article {2001ApJ...563..941S,
	title = {{Double-peaked X-Ray Lines from the Oxygen/Neon-rich Accretion Disk in 4U 1626-67}},
	journal = {\apj},
	volume = {563},
	year = {2001},
	note = {n/a},
	month = {dec},
	pages = {941-949},
	abstract = {{We report on a 39 ks observation of the 7.7 s low-mass X-ray binary pulsar 4U 1626-67 with the High Energy Transmission Grating Spectrometer (HETGS) on the Chandra X-Ray Observatory. This ultracompact system consists of a disk-accreting magnetic neutron star and a very low mass, hydrogen-depleted companion in a 42 minute binary. We have resolved the previously reported Ne/O emission line complex near 1 keV into Doppler pairs of broadened (\~{}2500 km s$^{-1}$ FWHM) lines from highly ionized Ne and O. In most cases, the blue and red line components are of comparable strength, with blueshifts of 1550-2610 km s$^{-1}$ and redshifts of 770-1900 km s$^{-1}$. The lines appear to originate in hot (\~{}10$^{6}$ K), dense material just below the X-ray-heated skin of the outer Keplerian accretion disk, or else possibly in a disk wind driven from the pulsar{\textquoteright}s magnetopause. The observed photoelectric absorption edges of Ne and O appear nearly an order of magnitude stronger than expected from interstellar material and are likely formed in cool, metal-rich material local to the source. Based on the inferred local abundance ratios, we argue that the mass donor in this binary is probably the 0.02 M$_{solar}$ chemically fractionated core of a C-O-Ne or O-Ne-Mg white dwarf which has previously crystallized. }
},
	doi = {10.1086/323988},
	author = {{Schulz}, N.~S. and {Chakrabarty}, D. and {Marshall}, H.~L. and {Canizares}, C.~R. and {Lee}, J.~C. and {Houck}, J.}
}
@article {2000MNRAS.318..857L,
	title = {{The X-ray variability of the Seyfert 1 galaxy MCG-6-30-15 from long ASCA and RXTE observations}},
	journal = {\mnras},
	volume = {318},
	year = {2000},
	note = {n/a},
	month = {nov},
	pages = {857-874},
	abstract = {{We present an analysis of the long Rossi X-ray Timing Explorer (RXTE) observation of the Seyfert 1 galaxy MCG-6-30-15, taken in 1997 July. We have previously used the data to place constraints for the first time on the iron abundance-reflection fraction relationship, and now expand the analysis to investigate in detail the spectral X-ray variability of the object. Our results show that the behaviour is complicated. We find clear evidence from colour ratios and direct spectral fitting that changes to the intrinsic photon index are taking place. In general, spectral hardening is evident during periods of diminished intensity, and in particular, a general trend for harder spectra is seen in the period following the hardest RXTE flare. Flux-correlated studies further show that the 3-10keV photon index {$\Gamma$}$_{3-10}$ steepens, while that in the 10-20keV band, {$\Gamma$}$_{10-20}$, flattens with flux. The largest changes come from the spectral index below 10keV however, changes in the intrinsic power-law slope (shown by changes in {$\Gamma$}$_{3-10}$), and reflection (shown by changes in {$\Gamma$}$_{10-20}$) both contribute in varying degrees to the overall spectral variability. We find that the iron-line flux F$_{Kα}$ is consistent with being constant over large time intervals on the order of days (although tentative evidence exists which show that F$_{Kα}$ changes on shorter time intervals of order {\l}t}\~{}10ks during time periods surrounding flare events), and has an equivalent width which anticorrelates with the continuum flux and reflection fraction. A possible interpretation for the iron-line flux constancy and the relative Compton reflection increase with flux from the flux-correlated data is an increasing ionization of the emitting disc surface, while spectral analysis of short time intervals surrounding flare events hints tentatively at observed spectral responses to the flare. We present a simple model for partial ionization where the bulk of the variability comes from within 6r$_{g}$. Temporal analysis further provides evidence for possible time ({\l}t}\~{}1000s) and phase ({\phis}\~{}0.6rad) lags. Finally, we report an apparent break in the power density spectrum (\~{}4-5{\times}10$^{-6}$Hz) and a possible 33-hour period. Estimates for the mass of the black hole in MCG-6-30-15 are discussed in the context of spectral and temporal findings. }
},
	doi = {10.1046/j.1365-8711.2000.03835.x},
	author = {{Lee}, J.~C. and {Fabian}, A.~C. and {Reynolds}, C.~S. and {Brandt}, W.~N. and {Iwasawa}, K.}
}
@article {2000ApJ...545L..81O,
	title = {{Chandra Observations of the X-Ray Narrow-Line Region in NGC 4151}},
	journal = {\apjl},
	volume = {545},
	year = {2000},
	note = {n/a},
	month = {dec},
	pages = {L81-L84},
	abstract = {{We present the first high-resolution X-ray spectrum of the Seyfert 1.5 galaxy NGC 4151. Observations with the Chandra High-Energy Transmission Grating Spectrometer reveal a spectrum dominated by narrow emission lines from a spatially resolved (1.6 kpc), highly ionized nebula. The X-ray narrow-line region is composite, consisting of both photoionized and collisionally ionized components. The X-ray emission lines have similar velocities, widths, and spatial extent to the optical emission lines, showing that they arise in the same region. The clouds in the narrow-line region must contain a large range of ionization states in order to explain both the optical and X-ray photoionized emission. Chandra data give the first direct evidence of X-ray line emission from a hot plasma (T\~{}10$^{7}$ K) that may provide pressure confinement for the cooler (T=3{\times}10$^{4}$ K) photoionized clouds. }
},
	doi = {10.1086/317890},
	author = {{Ogle}, P.~M. and {Marshall}, H.~L. and {Lee}, J.~C. and {Canizares}, C.~R.}
}
@article {2000ApJ...545L.135S,
	title = {{X-Ray Line Emission from the Hot Stellar Wind of {\th}etas}$^{1}$ Orionis C}},
	journal = {\apjl},
	volume = {545},
	year = {2000},
	note = {n/a},
	month = {dec},
	pages = {L135-L139},
	abstract = {{We present a first emission-line analysis of a high-resolution X-ray spectrum of the stellar wind of {\th}etas}$^{1}$ Ori C obtained with the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory. The spectra are resolved into a large number of emission lines from H- and He-like O, Ne, Mg, Si, S, Ar, and Fe ions. The He-like Fe XXV and Li-like Fe XXIV appear quite strong, indicating very hot emitting regions. From H/He flux ratios as well as from Fe He/Li emission measure ratios, we deduce temperatures ranging from 0.5 to 6.1{\times}10$^{7}$ K. The He triplets are very sensitive to density as well. At these temperatures the relative strengths of the intercombination and forbidden lines indicate electron densities well above 10$^{12}$ cm$^{-3}$. The lines appear significantly broadened, from which we deduce a mean velocity of 770 km s$^{-1}$ with a spread between 400 and 2000 km s$^{-1}$. Along with results of the deduced emission measure, we conclude that the X-ray emission could originate in dense and hot regions with a characteristic size of less then 4{\times}10$^{10}$ cm. }
},
	doi = {10.1086/317891},
	author = {{Schulz}, N.~S. and {Canizares}, C.~R. and {Huenemoerder}, D. and {Lee}, J.~C.}
}
@article {1999ApJ...517..565P,
	title = {{Measurements of Omega and Lambda from 42 High-Redshift Supernovae}},
	journal = {\apj},
	volume = {517},
	year = {1999},
	note = {n/a},
	month = {jun},
	pages = {565-586},
	abstract = {{We report measurements of the mass density, Omega\_M, and cosmological-constant energy density, Omega\_Lambda, of the universe based on the analysis of 42 type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fitted jointly with a set of supernovae from the Cal{\'a}n/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. All supernova peak magnitudes are standardized using a SN Ia light-curve width-luminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation 0.8Omega\_M-0.6Omega\_Lambda\~{}-0.2+/-0.1 in the region of interest (Omega\_M{\l}t}\~{}1.5). For a flat (Omega\_M+Omega\_Lambda=1) cosmology we find Omega\^{}flat\_M=0.28\^{}+0.09\_-0.08 (1 sigma statistical) \^{}+0.05\_-0.04 (identified systematics). The data are strongly inconsistent with a Lambda=0 flat cosmology, the simplest inflationary universe model. An ope
},
	doi = {10.1086/307221},
	author = {{Perlmutter}, S. and {Aldering}, G. and {Goldhaber}, G. and {Knop}, R.~A. and {Nugent}, P. and {Castro}, P.~G. and {Deustua}, S. and {Fabbro}, S. and {Goobar}, A. and {Groom}, D.~E. and {Hook}, I.~M. and {Kim}, A.~G. and {Kim}, M.~Y. and {Lee}, J.~C. and {Nunes}, N.~J. and {Pain}, R. and {Pennypacker}, C.~R. and {Quimby}, R. and {Lidman}, C. and {Ellis}, R.~S. and {Irwin}, M. and {McMahon}, R.~G. and {Ruiz-Lapuente}, P. and {Walton}, N. and {Schaefer}, B. and {Boyle}, B.~J. and {Filippenko}, A.~V. and {Matheson}, T. and {Fruchter}, A.~S. and {Panagia}, N. and {Newberg}, H.~J.~M. and {Couch}, W.~J. and {Supernova Cosmology Project}}
}
@article {1999MNRAS.310..973L,
	title = {{First constraints on iron abundance versus reflection fraction from the Seyfert 1 galaxy MCG-6-30-15}},
	journal = {\mnras},
	volume = {310},
	year = {1999},
	note = {n/a},
	month = {dec},
	pages = {973-981},
	abstract = {{We report on a joint ASCA and RXTE observation spanning an \~{}400ks time interval of the bright Seyfert 1 galaxy MCG-6-30-15. The data clearly confirm the presence of a broad skewed iron line (W$_{Kα}$\~{}266eV) and Compton reflection continuum at higher energies reported in our previous paper. We also investigate whether the gravitational and Doppler effects, which affect the iron line, may also be manifest in the reflected continuum. The uniqueness of this data set is underlined by the extremely good statistics that we obtain from the approximately four million photons that make up the 2-20keV RXTE PCA spectrum alone. This, coupled with the high energy coverage of HEXTE and the spectral resolution of ASCA in the iron line regime, has allowed us to constrain the relationship between abundance and reflection fraction for the first time at the 99per cent confidence level. The reflection fraction is entirely consistent with a flat disc, i.e. the cold material subtends 2{$π$} sr at the source, to an accuracy of 20per cent. Monte Carlo simulations show that the observed strong iron line intensity is explained by an overabundance of iron by a factor of \~{}2 and an underabundance of the lower-Z elements by a similar factor. By considering non-standard abundances, a clear and consistent picture can be made in which both the iron line and reflection continuum come from the same material such as, e.g., an accretion disc. }
},
	doi = {10.1046/j.1365-8711.1999.02999.x},
	author = {{Lee}, J.~C. and {Fabian}, A.~C. and {Brandt}, W.~N. and {Reynolds}, C.~S. and {Iwasawa}, K.}
}
@article {1998MNRAS.300..583L,
	title = {{AnRXTEobservation of the Seyfert 1 galaxy MCG-6-30-15: X-ray reflection and the iron abundance}},
	journal = {\mnras},
	volume = {300},
	year = {1998},
	note = {n/a},
	month = {oct},
	pages = {583-588},
	abstract = {{We report on a 50-ks observation of the bright Seyfert 1 galaxy MCG-6-30-15 with the Rossi X-ray Timing Explorer. The data clearly show the broad fluorescent iron line (equivalent width \~{} 250 eV) and the Compton reflection continuum at higher energies. A comparison of the iron line and the reflection continuum has enabled us to constrain the reflective fraction and the elemental abundances in the accretion disc. Temporal studies provide evidence that spectral variability is a result of changes in both the amount of reflection seen and the properties of the primary X-ray source itself. }
},
	doi = {10.1046/j.1365-8711.1998.01925.x},
	author = {{Lee}, J.~C. and {Fabian}, A.~C. and {Reynolds}, C.~S. and {Iwasawa}, K. and {Brandt}, W.~N.}
}
@conference {1997thsu.conf..785P,
	title = {{The Type Ia SNe rate at z \~{} 0.4}},
	booktitle = {NATO ASIC Proc. 486: Thermonuclear Supernovae},
	year = {1997},
	note = {n/a},
	pages = {785},
	abstract = {n/a},
	author = {{Pain}, R. and {} and et al},
	editor = {{Ruiz-Lapuente}, P. and {Canal}, R. and {Isern}, J.}
}
@article {1997ApJ...476L..63K,
	title = {{Implications for the Hubble Constant from the First Seven Supernovae at Z 0.35}},
	journal = {\apjl},
	volume = {476},
	year = {1997},
	note = {n/a},
	month = {feb},
	pages = {L63},
	abstract = {{The Supernova Cosmology Project has discovered over 28 supernovae (SNs) at 0.35 {\l}t} z {\l}t} 0.65 in an ongoing program that uses Type Ia SNs (SN Ia{\textquoteright}s) as high-redshift distance indicators. Here we present measurements of the ratio between the locally observed and global Hubble constants, H$^{L}$$_{0}$/H$^{G}$$_{0}$ , based on the first seven SNs of this high-redshift data set compared with 18 SNs at z {\l}t}= 0.1 from the Calan/Tololo survey. If Omega M {\l}t}= 1, then light-curve width corrected SN magnitudes yield H$^{L}$$_{0}$/H$^{G}$$_{0}$ {\l}t} 1.10 (95\% confidence level) in both a Lamda = 0 and a flat universe. The analysis using the SN Ia{\textquoteright}s as standard candles without a light-curve width correction yields similar results. These results rule out the hypothesis that the discrepant ages of the Universe derived from globular clusters and recent measurements of the Hubble constant are attributable to a locally underdense bubble. Using the Cepheid-distance{\textendash}calibrated absolute magnitudes for SN Ia{\textquoteright}s of Sandage et al., we can also measure the global Hubble constant, H$^{G}$$_{0}$ . If Omega M {\gt}= 0.2, we find that H$^{G}$$_{0}$ {\l}t} 70 km s-1 Mpc-1 in a Lamda = 0 universe and H$^{G}$$_{0}$ {\l}t} 78 km s-1 Mpc-1 in a flat universe, correcting the distant and local SN apparent magnitudes for light-curve width. Lower results for H$^{G}$$_{0}$ are obtained if the magnitudes are not width-corrected. }
},
	doi = {10.1086/310507},
	author = {{Kim}, A.~G. and {Gabi}, S. and {Goldhaber}, G. and {Groom}, D.~E. and {Hook}, I.~M. and {Kim}, M.~Y. and {Lee}, J.~C. and {Pennypacker}, C.~R. and {Perlmutter}, S. and {Small}, I.~A. and {Goobar}, A. and {Pain}, R. and {Ellis}, R.~S. and {McMahon}, R.~G. and {Boyle}, B.~J. and {Bunclark}, P.~S. and {Carter}, D. and {Irwin}, M.~J. and {Glazebrook}, K. and {Newberg}, H.~J.~M. and {Filippenko}, A.~V. and {Matheson}, T. and {Dopita}, M. and {Couch}, W.~J.}
}
@article {1997ApJ...483..565P,
	title = {{Measurements of the Cosmological Parameters Omega and Lambda from the First Seven Supernovae at Z {\gt}= 0.35}},
	journal = {\apj},
	volume = {483},
	year = {1997},
	note = {n/a},
	month = {jul},
	pages = {565},
	abstract = {{We have developed a technique to systematically discover and study high-redshift supernovae that can be used to measure the cosmological parameters. We report here results based on the initial seven of more than 28 supernovae discovered to date in the high-redshift supernova search of the Supernova Cosmology Project. We find an observational dispersion in peak magnitudes of sigma \_$\{$M$_{B}$$\}$=0.27 ; this dispersion narrows to sigma \_$\{$M$_{B}$,$\{$corr$\}$$\}$=0.19 after {\textquoteright}{\textquoteright}correcting{\textquoteright}{\textquoteright} the magnitudes using the light-curve {\textquoteright}{\textquoteright}width-luminosity{\textquoteright}{\textquoteright} relation found for nearby (z {\l}t}= 0.1) Type Ia supernovae from the Calan/Tololo survey (Hamuy et al.). Comparing light-curve width{\textendash}corrected magnitudes as a function of redshift of our distant (z = 0.35{\textendash}0.46) supernovae to those of nearby Type Ia supernovae yields a global measurement of the mass density, Omega \_$\{$$\{$M$\}$$\}$=0.88\^{}$\{$+0.69$\}$\_$\{$-0.60$\}$ for a Lamda = 0 cosmology. For a spatially flat universe (i.e., Omega M + Omega Lamda = 1), we find Omega \_$\{$$\{$M$\}$$\}$=0.94\^{}$\{$+0.34$\}$\_$\{$-0.28$\}$ or, equivalently, a measurement of the cosmological constant, Omega \_$\{$ Lamda $\}$=0.06\^{}$\{$+0.28$\}$\_$\{$-0.34$\}$ ({\l}t}0.51 at the 95\% confidence level). For the more general Friedmann-Lemaitre cosmologies with independent Omega M and Omega Lamda , the results are presented as a confidence region on the Omega M- Omega Lamda plane. This region does not correspond to a unique value of the deceleration parameter q0. We present analyses and checks for statistical and systematic errors and also show that our results do not depend on the specifics of the width-luminosity correction. The results for Omega Lamda -versus- Omega M are inconsistent with Lamda -dominated, low-density, flat cosmologies that have been proposed to reconcile the ages of globular cluster stars with higher Hubble constant values. }
},
	doi = {10.1086/304265},
	author = {{Perlmutter}, S. and {Gabi}, S. and {Goldhaber}, G. and {Goobar}, A. and {Groom}, D.~E. and {Hook}, I.~M. and {Kim}, A.~G. and {Kim}, M.~Y. and {Lee}, J.~C. and {Pain}, R. and {Pennypacker}, C.~R. and {Small}, I.~A. and {Ellis}, R.~S. and {McMahon}, R.~G. and {Boyle}, B.~J. and {Bunclark}, P.~S. and {Carter}, D. and {Irwin}, M.~J. and {Glazebrook}, K. and {Newberg}, H.~J.~M. and {Filippenko}, A.~V. and {Matheson}, T. and {Dopita}, M. and {Couch}, W.~J. and {Supernova Cosmology Project}}
}
