@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}
}
