We present a public data release of halo catalogs from a suite of 125cosmological N-body simulations from the ABACUS project. The simulationsspan 40 wCDM cosmologies centered on the Planck 2015 cosmology at twomass resolutions, 4 × 10¹⁰ h ^-1 M_⊙ and 1 × 10¹⁰ h ^-1 M_⊙, in 1.1 h ^-1 Gpc and 720 h^-1 Mpc boxes, respectively. The boxes are phase-matchedto suppress sample variance and isolate cosmology dependence. Additionalvolume is available via 16 boxes of fixed cosmology and varied phase; afew boxes of single-parameter excursions from Planck 2015 are alsoprovided. Catalogs spanning z = 1.5 to 0.1 are available forfriends-of-friends and ROCKSTAR halo finders and include particlesubsamples. All data products are available at https://lgarrison.github.io/AbacusCosmos.

We develop a formalism for measuring the cosmological distance scalefrom baryon acoustic oscillations (BAO) using the cross-correlation of asparse redshift survey with a denser photometric sample. This reducesthe shot noise that would otherwise affect the autocorrelation of thesparse spectroscopic map. As a proof of principle, we make the firston-sky application of this method to a sparse sample defined as the z> 0.6 tail of the Sloan Digital Sky Survey's (SDSS) BOSS/CMASS sampleof galaxies and a dense photometric sample from SDSS DR9. We find a2.8σ preference for the BAO peak in the cross-correlation at aneffective z = 0.64, from which we measure the angular diameter distanceD_M(z = 0.64) = (2418 ± 73 Mpc)(r_s/r_s,fid). Accordingly, we expect that using this method to combinesparse spectroscopy with the deep, high-quality imaging that is just nowbecoming available will enable higher precision BAO measurements thanpossible with the spectroscopy alone.

We investigate the potential sources of theoretical systematics in theanisotropic Baryon Acoustic Oscillation (BAO) distance scalemeasurements from the clustering of galaxies in configuration spaceusing the final Data Release (DR12) of the Baryon OscillationSpectroscopic Survey (BOSS). We perform a detailed study of the impacton BAO measurements from choices in the methodology such as fiducialcosmology, clustering estimators, random catalogues, fitting templates,and covariance matrices. The theoretical systematic uncertainties in BAOparameters are found to be 0.002 in the isotropic dilation α and0.003 in the quadrupolar dilation ɛ. The leading source ofsystematic uncertainty is related to the reconstruction techniques.Theoretical uncertainties are sub-dominant compared with the statisticaluncertainties for BOSS survey, accounting 0.2σ_stat forα and 0.25σ_stat for ɛ(σ_{α, stat} ˜ 0.010 andσ_{ɛ, stat} ˜ 0.012, respectively). We alsopresent BAO-only distance scale constraints from the anisotropicanalysis of the correlation function. Our constraints on the angulardiameter distance D_A(z) and the Hubble parameter H(z),including both statistical and theoretical systematic uncertainties, are1.5 per cent and 2.8 per cent at z_eff = 0.38, 1.4 per centand 2.4 per cent at z_eff = 0.51, and 1.7 per cent and 2.6 percent at z_eff = 0.61. This paper is part of a set thatanalyses the final galaxy clustering data set from BOSS. Themeasurements and likelihoods presented here are cross-checked with otherBAO analysis in Alam et al. The systematic error budget concerning themethodology on post-reconstruction BAO analysis presented here is usedin Alam et al. to produce the final cosmological constraints from BOSS.

We present measurements of the Baryon Acoustic Oscillation (BAO) scalein redshift-space using the clustering of quasars. We consider a sampleof 147 000 quasars from the extended Baryon Oscillation SpectroscopicSurvey (eBOSS) distributed over 2044 square degrees with redshifts 0.8< z < 2.2 and measure their spherically averaged clustering inboth configuration and Fourier space. Our observational data set and the1400 simulated realizations of the data set allow us to detect apreference for BAO that is greater than 2.8σ. We determine thespherically averaged BAO distance to z = 1.52 to 3.8 per cent precision:D_V(z = 1.52) = 3843 ± 147(r_d/r_d,fid)Mpc. This is the first time the location of the BAO featurehas been measured between redshifts 1 and 2. Our result is fullyconsistent with the prediction obtained by extrapolating the Planck flatΛCDM best-fitting cosmology. All of our results are consistentwith basic large-scale structure (LSS) theory, confirming quasars to bea reliable tracer of LSS, and provide a starting point for numerouscosmological tests to be performed with eBOSS quasar samples. We combineour result with previous, independent, BAO distance measurements toconstruct an updated BAO distance-ladder. Using these BAO data alone andmarginalizing over the length of the standard ruler, we findΩ_Λ > 0 at 6.6σ significance whentesting a ΛCDM model with free curvature.

We search for a galaxy clustering bias due to a modulation of galaxynumber with the baryon-dark matter relative velocity resulting fromrecombination-era physics. We find no detected signal and place theconstraint b_v < 0.01 on the relative velocity bias for theCMASS galaxies. This bias is an important potential systematic of baryonacoustic oscillation (BAO) method measurements of the cosmic distancescale using the two-point clustering. Our limit on the relative velocitybias indicates a systematic shift of no more than 0.3 per cent rms inthe distance scale inferred from the BAO feature in the BOSS two-pointclustering, well below the 1 per cent statistical error of thismeasurement. This constraint is the most stringent currently availableand has important implications for the ability of upcoming large-scalestructure surveys such as the Dark Energy Spectroscopic Instrument(DESI) to self-protect against the relative velocity as a possiblesystematic.

We present a machine-learning approach for estimating galaxy clustermasses from Chandra mock images. We utilize a Convolutional NeuralNetwork (CNN), a deep machine learning tool commonly used in imagerecognition tasks. The CNN is trained and tested on our sample of 7,896Chandra X-ray mock observations, which are based on 329 massive clustersfrom the IllustrisTNG simulation. Our CNN learns from a low resolutionspatial distribution of photon counts and does not use spectralinformation. Despite our simplifying assumption to neglect spectralinformation, the resulting mass values estimated by the CNN exhibitsmall bias in comparison to the true masses of the simulated clusters(-0.02 dex) and reproduce the cluster masses with low intrinsic scatter,

We present the GeneRalized ANd Differentiable Halo OccupationDistribution (GRAND-HOD) routine that generalizes the standard fiveparameter halo occupation distribution (HOD) model with varioushalo-scale physics and assembly bias. We describe the methodology offour different generalizations: satellite distribution generalization,velocity bias, closest approach distance generalization, and assemblybias. We showcase the signatures of these generalizations in the 2-pointcorrelation function (2PCF) and the squeezed 3-point correlationfunction (squeezed 3PCF). We identify generalized HOD prescriptions thatare nearly degenerate in the projected 2PCF and demonstrate that thesedegeneracies are broken in the redshift-space anisotropic 2PCF and thesqueezed 3PCF. We also discuss the possibility of identifyingdegeneracies in the anisotropic 2PCF and further demonstrate the extraconstraining power of the squeezed 3PCF on galaxy-halo connectionmodels. We find that within our current HOD framework, the anisotropic2PCF can predict the squeezed 3PCF better than its statistical error.This implies that a discordant squeezed 3PCF measurement could falsifythe particular HOD model space. Alternatively, it is possible thatfurther generalizations of the HOD model would open opportunities forthe squeezed 3PCF to provide novel parameter measurements. The GRAND-HODPYTHON package is publicly available athttps://github.com/SandyYuan/GRAND-HOD.

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has beenin operation since 2014 July. This paper describes the second datarelease from this phase, and the 14th from SDSS overall (making thisData Release Fourteen or DR14). This release makes the data taken bySDSS-IV in its first two years of operation (2014-2016 July)public. Like all previous SDSS releases, DR14 is cumulative, includingthe most recent reductions and calibrations of all data taken by SDSSsince the first phase began operations in 2000. New in DR14 is the firstpublic release of data from the extended Baryon OscillationSpectroscopic Survey; the first data from the second phase of the ApachePoint Observatory (APO) Galactic Evolution Experiment (APOGEE-2),including stellar parameter estimates from an innovative data-drivenmachine-learning algorithm known as “The Cannon” and almosttwice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA)survey as were in the previous release (N = 2812 in total). This paperdescribes the location and format of the publicly available data fromthe SDSS-IV surveys. We provide references to the important technicalpapers describing how these data have been taken (both targeting andobservation details) and processed for scientific use. The SDSS web site(www.sdss.org) has been updated forthis release and provides links to data downloads, as well as tutorialsand examples of data use. SDSS-IV is planning to continue to collectastronomical data until 2020 and will be followed by SDSS-V.

We present a high-fidelity realization of the cosmological $N$-bodysimulation from the Schneider et al. (2016) code comparison project. Thesimulation was performed with our Abacus $N$-body code, which offershigh force accuracy, high performance, and minimal particle integrationerrors. The simulation consists of $2048^3$ particles in a $500\h^{-1}\mathrm{Mpc}$ box, for a particle mass of $1.2\times 10^9\h^{-1}\mathrm{M}_\odot$ with $10\ h^{-1}\mathrm{kpc}$ spline softening.Abacus executed 1052 global time steps to $z=0$ in 107 hours on onedual-Xeon, dual-GPU node, for a mean rate of 23 million particles persecond per step. We find Abacus is in good agreement with Ramses andPKDGrav and less so with Gadget-3. We validate our choice of time stepby halving the step size and find sub-percent differences in the power

We present an iterative method to reconstruct the linear-theory initialconditions from the late-time cosmological matter density field, withthe intent of improving the recovery of the cosmic distance scale fromthe baryon acoustic oscillations. We present tests using the dark matterdensity field in both real and redshift space generated from an N-bodysimulation. In redshift space at z = 0.5, we find that the reconstructeddisplacement field using our iterative method are more than 80 per centcorrelated with the true displacement field of the dark matter particleson scales k < 0.10 h Mpc^-1. Furthermore, we show that thetwo-point correlation function of our reconstructed density fieldmatches that of the initial density field substantially better,especially on small scales (<40 h^-1 Mpc). Ourredshift-space results are improved if we use an anisotropic smoothingso as to account for the reduced small-scale information along the lineof sight in redshift space.

We present an original phenomenological model to describe the evolutionof galaxy number counts, morphologies, and spectral energy distributionsacross a wide range of redshifts (0.2< z< 15) and stellar masses[{log}(M/{M}_⊙ )≥slant 6]. Our model follows observedmass and luminosity functions of both star-forming and quiescentgalaxies, and reproduces the redshift evolution of colors, sizes, starformation, and chemical properties of the observed galaxy population.Unlike other existing approaches, our model includes a self-consistenttreatment of stellar and photoionized gas emission and dust attenuationbased on the BEAGLE tool. The mock galaxy catalogs generated with ournew model can be used to simulate and optimize extragalactic surveyswith future facilities such as the James Webb Space Telescope (JWST),and to enable critical assessments of analysis procedures,interpretation tools, and measurement systematics for both photometricand spectroscopic data. As a first application of this work, we makepredictions for the upcoming JWST Advanced Deep Extragalactic Survey(JADES), a joint program of the JWST/NIRCam and NIRSpec Guaranteed TimeObservations teams. We show that JADES will detect, with NIRCam imaging,1000s of galaxies at z ≳ 6, and 10s at z ≳ 10 at{m}_{AB}≲ 30 (5σ) within the 236 arcmin²of the survey. The JADES data will enable accurate constraints on theevolution of the UV luminosity function at z > 8, and resolve thecurrent debate about the rate of evolution of galaxies at z ≳ 8.Ready-to-use mock catalogs and software to generate new realizations arepublicly available as the JAdes extraGalactic Ultradeep ArtificialRealizations (JAGUAR) package.

Covariance matrix estimation is a persistent challenge for cosmology. Wefocus on a class of model covariance matrices that can be generated withhigh accuracy and precision, using a tiny fraction of the computationalresources that would be required to achieve comparably precisecovariance matrices using mock catalogues. In previous work, the freeparameters in these models were determined using sample covariancematrices computed using a large number of mocks, but we demonstrate thatthose parameters can be estimated consistently and with good precisionby applying jackknife methods to a single survey volume. This enablesmodel covariance matrices that are calibrated from data alone, with noreference to mocks.

The Dark Energy Spectroscopic Instrument (DESI) is under construction tomeasure the expansion history of the Universe using the Baryon AcousticOscillation technique. The spectra of 35 million galaxies and quasarsover 14000 square degrees will be measured during the life of theexperiment. A new prime focus corrector for the KPNO Mayall telescopewill deliver light to 5000 fiber optic positioners. The fibers in turnfeed ten broad-band spectrographs. We present an overview of theinstrumentation, the main technical requirements and challenges, and thecurrent status of the project.

The DESI Legacy Imaging Surveys are a combination of three publicprojects (the Dark Energy Camera Legacy Survey, the Beijing-Arizona SkySurvey, and the Mayall z-band Legacy Survey) that will jointly imageapproximately 14,000 deg^2 of the extragalactic sky visible from thenorthern hemisphere in three optical bands (g, r, and z) usingtelescopes at the Kitt Peak National Observatory and the Cerro TololoInter-American Observatory. The combined survey footprint is split intotwo contiguous areas by the Galactic plane. The optical imaging isconducted using a unique strategy of dynamically adjusting the exposuretimes and pointing selection during observing that results in a surveyof nearly uniform depth. In addition to calibrated images, the projectis delivering a catalog, constructed by using a probabilisticinference-based approach to estimate source shapes and brightnesses. Thecatalog includes photometry from the grz optical bands and from fourmid-infrared bands (at 3.4, 4.6, 12 and 22 micorons) observed by theWide-field Infrared Survey Explorer (WISE) satellite during its fulloperational lifetime. The project plans two public data releases eachyear. All the software used to generate the catalogs is also releasedwith the data. This paper provides an overview of the Legacy Surveysproject.

We present an algorithm enabling computation of the anisotropicredshift-space galaxy three-point correlation function (3PCF) scaling asN², with N the number of galaxies. Our previous work showedhow to compute the isotropic 3PCF with this scaling by expanding theradially binned density field around each galaxy in the survey intospherical harmonics and combining these coefficients to form multipolemoments. The N² scaling occurred because this approach neverexplicitly required the relative angle between a galaxy pair about theprimary galaxy. Here, we generalize this work, demonstrating that in thepresence of azimuthally symmetric anisotropy produced by redshift-spacedistortions (RSD), the 3PCF can be described by two triangle sidelengths, two independent total angular momenta, and a spin. This basisfor the anisotropic 3PCF allows its computation with negligibleadditional work over the isotropic 3PCF. We also present the covariancematrix of the anisotropic 3PCF measured in this basis. Our algorithmtracks the full 5D redshift-space 3PCF, uses an accurate line of sightto each triplet, is exact in angle, and easily handles edge correction.It will enable use of the anisotropic large-scale 3PCF as a probe of RSDin current and upcoming large-scale redshift surveys.

We probe the higher-order galaxy clustering in the final data release(DR12) of the Sloan Digital Sky Survey using germ-grain MinkowskiFunctionals (MFs). Our data selection contains 979,430 BOSS galaxiesfrom both the northern and southern galactic caps over the redshiftrange 0.2 - 0.6. We extract the higher-order parts of the MFs and finddeviations from the case without higher order MFs with chi-squaredvalues of order 1000 for 24 degrees of freedom across the entire dataselection. We show the MFs to be sensitive to contributions up to thefive-point correlation function across the entire data selection. Wemeasure significant redshift evolution in the higher-order functionalsfor the first time, with a percentage growth between redshift bins of

We explore the connection between the UV luminosity functions (LFs) ofhigh-z galaxies and the distribution of stellar masses and starformation histories (SFHs) in their host dark matter halos. We provide abaseline for a redshift-independent star formation efficiency model towhich observations and models can be compared. Our model assigns a starformation rate (SFR) to each dark matter halo based on the growth rateof the halo and a redshift-independent star formation efficiency. Thedark matter halo accretion rate is obtained from a high-resolutionN-body simulation in order to capture the stochasticity in accretionhistories and to obtain spatial information for the distribution ofgalaxies. The halo mass dependence of the star formation efficiency iscalibrated at z = 4 by requiring a match to the observed UV LF at thisredshift. The model then correctly predicts the observed UV LF at z =5–10. We present predictions for the UV luminosity and stellarmass functions, JWST number counts, and SFHs. In particular, we find astellar-to-halo mass relation at z = 4–10 that scales with halomass at M _h < 10¹¹ M _⊙ as M_⋆ ∝ M _h², with anormalization that is higher than the relation inferred at z = 0. Theaverage SFRs increase as a function of time to z = 4, although there is

We present a color-based method for identifying red giants based on thePan-STARRS grz and WISE W1 and W2 photometry. We utilize a subsample ofbright stars with precise parallaxes from Gaia’s second datarelease (DR2) to verify that the color-based selection reliablyseparates dwarfs from giants. The selection is conservative in the sense

We perform a tomographic baryon acoustic oscillations (BAO) analysisusing the monopole, quadrupole and hexadecapole of the redshift-spacegalaxy power spectrum measured from the pre-reconstructed combinedgalaxy sample of the completed Sloan Digital Sky Survey BaryonOscillation Spectroscopic Survey (BOSS) Data Release12 covering theredshift range of 0.20 < z < 0.75. By allowing for overlap betweenneighbouring redshift slices, we successfully obtained the isotropic andanisotropic BAO distance measurements within nine redshift slices to aprecision of 1.5-3.4 per cent for D_V/r_d, 1.8-4.2per cent for D_A/r_d and 3.7-7.5 per cent for Hr_d, depending on effective redshifts. We provide our BAOmeasurement of D_A/r_d and H r_d with thefull covariance matrix, which can be used for cosmological implications.Our measurements are consistent with those presented in Alam et al., inwhich the BAO distances are measured at three effective redshifts. Weconstrain dark energy parameters using our measurements and find animprovement of the Figure-of-Merit of dark energy in general due to thetemporal BAO information resolved. This paper is a part of a set thatanalyses the final galaxy clustering data set from BOSS.

We perform a tomographic baryon acoustic oscillations (BAOs) analysisusing the two-point galaxy correlation function measured from thecombined sample of Baryon Oscillation Spectroscopic Survey Data Release12 (BOSS DR12), which covers the redshift range of 0.2 < z < 0.75.Upon splitting the sample into multiple overlapping redshift slices toextract the redshift information of galaxy clustering, we obtain ameasurement of D_A(z)/r_d and H(z)r_d atnine effective redshifts with the full covariance matrix calibratedusing MultiDark-Patchy mock catalogues. Using the reconstructed galaxycatalogues, we obtain the precision of 1.3-2.2 per cent forD_A(z)/r_d and 2.1-6.0 per cent forH(z)r_d. To quantify the gain from the tomographicinformation, we compare the constraints on the cosmological parametersusing our nine-bin BAO measurements, the consensus three-bin BAO andredshift space distortion measurements at three effective redshifts inAlam et al., and the non-tomographic (one-bin) BAO measurement at asingle effective redshift. Comparing the nine-bin with one-binconstraint result, it can improve the dark energy Figure of Merit by afactor of 1.24 for the Chevallier-Polarski-Linder parametrization forequation-of-state parameter w_DE. The errors of w₀and w_a from nine-bin constraints are slightly improved whencompared to the three-bin constraint result.