Kenneth C. Wong

PRIMUS: Constraints on Star Formation Quenching and Galaxy Merging, and the Evolution of the Stellar Mass Function From z=0-1

We measure the evolution of the stellar mass function (SMF) from z = 0−1 using multi-wavelength imaging and spectroscopic redshifts from the PRism MUlti-object Survey (PRIMUS) and the Sloan Digital Sky Survey (SDSS). From PRIMUS we construct an i < 23 flux-limited sample of ∼ 40,000 galaxies at z = 0.2 − 1.0 over five fields totaling ≈ 5.5 deg 2 , and from the SDSS we select ∼ 170,000 galaxies atz = 0.01−0.2 that we analyze consistently with respect to PRIMUS to minimize systematic errors in our evolutionary measurements. We find that the SMF of all galaxies evolves relatively little since z = 1, although we do find evidence for mass assembly downsizing; we measure a ≈ 30% increase in the number density of ∼ 10 10 M⊙ galaxies sincez ≈ 0.6, and a . 10% change in the number density of all & 10 11 M⊙ galaxies since z ≈ 1. Dividing the sample into star-forming and quiescent using an evolving cut in specific star-formation rate, we find that the number density of ∼ 10 10 M⊙ star-forming galaxies stays relatively constant since z ≈ 0.6, whereas the space-density of & 10 11 M⊙ star-forming galaxies decreases by ≈ 50% between z ≈ 1 and z ≈ 0. Meanwhile, the number density of ∼ 10 10 M⊙ quiescent galaxies increases steeply towards low redshift, by a factor of ∼ 2 − 3 since z ≈ 0.6, while the number of massive quiescent galaxies remains approximately constant since z ≈ 1. These results suggest that the rate at which star-forming galaxies are quenched increases with decreasing stellar mass, but that the bulk of the stellar mass buildup within the quiescent population occurs around ∼ 10 10.8 M⊙. In addition, we conclude that mergers do not appear to be a dominant channel for the stellar mass buildup of galaxies at z < 1, even among massive (& 10 11 M⊙) quiescent galaxies. Subject headings: Surveys – galaxies: evolution – galaxies: high-redshift – cosmology: large-scale structure of universe

H0LiCOW - V. New COSMOGRAIL time delays of HE 0435-1223: H0 to 3.8 per cent precision from strong lensing in a flat ΛCDM model

We present a new measurement of the Hubble Constant H-0 and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time delays. First, we measure the time delay of HE 0435-1223 from 13-yr light curves obtained as part of the COSMOGRAIL project. Companion papers detail the modelling of the main deflectors and line-of-sight effects, and how these data are combined to determine the time-delay distance of HE 0435-1223. Crucially, the measurements are carried out blindly with respect to cosmological parameters in order to avoid confirmation bias. We then combine the time-delay distance of HE 0435-1223 with previous measurements from systems B1608+656 and RXJ1131-1231 to create a Time Delay Strong Lensing probe (IDSL). In flat A cold dark matter (ACDM) with free matter and energy density, we find H-0 = 71.9(-3.0)(+2.4) km s(-1) Mpc(-1) and Omega(Lambda) = 0.62(-0.35)(+0.24) This measurement is completely independent of, and in agreement with, the local distance ladder measurements of H-0. We explore more general cosmological models combining TDSL with other probes, illustrating its power to break degeneracies inherent to other methods. The joint constraints from IDSL and Planck are H-0 = 69.2(-2.2)(+1.4) km s(-1) Mpc(-1), Omega(Lambda) = 0.70(-0.01)(+0.01) and Omega(k) = 0.003(-0.006)(+0.004) in open ACDM and H-0 = 79.0(-4.2)(+4.4) km s(-1) Mpc(-1), Omega(de) = 0.77(-0.03)(+0.02) and w = -1.38(-0.16)(+0.14) in flat wCDM. In combination with Planck and baryon acoustic oscillation data, when relaxing the constraints on the numbers of relativistic species we find N-eff = 3.34(-0.21)(+0.21) in N-eff Lambda CDM and when relaxing the total mass of neutrinos we find Sigma rn(nu) <= 0.182 eV in m(nu) Lambda CDM. Finally, in an open wCDM in combination with Planck and cosmic microwave background lensing, we find H-0 = 77.9(-4.2)(+5.0) km s(-1) Mpc(-1), Omega(de) = 0.77(-0.03)(+0.03), Omega(k) = -0.003(-0.004)(+0.004) and w = -1.37(-0.23)(+0.18).

THE PRISM MULTI-OBJECT SURVEY (PRIMUS). II. DATA REDUCTION AND REDSHIFT FITTING

The PRIsm MUlti-object Survey (PRIMUS) is a spectroscopic galaxy redshift survey to z ~ 1 completed with a low-dispersion prism and slitmasks allowing for simultaneous observations of ~2500 objects over 0.18 deg2. The final PRIMUS catalog includes ~130,000 robust redshifts over 9.1 deg2. In this paper, we summarize the PRIMUS observational strategy and present the data reduction details used to measure redshifts, redshift precision, and survey completeness. The survey motivation, observational techniques, fields, target selection, slitmask design, and observations are presented in Coil et al. Comparisons to existing higher-resolution spectroscopic measurements show a typical precision of σ z /(1 + z) = 0.005. PRIMUS, both in area and number of redshifts, is the largest faint galaxy redshift survey completed to date and is allowing for precise measurements of the relationship between active galactic nuclei and their hosts, the effects of environment on galaxy evolution, and the build up of galactic systems over the latter half of cosmic history.

H0LiCOW - I. H0 Lenses in COSMOGRAIL's Wellspring: program overview

Strong gravitational lens systems with time delays between the multiple images allow measurements of time-delay distances, which are primarily sensitive to the Hubble constant that is key to probing dark energy, neutrino physics and the spatial curvature of the Universe, as well as discovering new physics. We present H0LiCOW (H-0 Lenses in COSMOGRAILs Wellspring), a program that aims to measure H-0 with <3.5 per cent uncertainty from five lens systems (B1608+ 656, RXJ1131-1231, HE 0435-1223, WFI2033-4723 and HE 1104-1805). We have been acquiring (1) time delays through COSMOGRAIL and Very Large Array monitoring, (2) high-resolution Hubble Space Telescope imaging for the lens mass modelling, (3) wide-field imaging and spectroscopy to characterize the lens environment and (4) moderate-resolution spectroscopy to obtain the stellar velocity dispersion of the lenses for mass modelling. In cosmological models with one-parameter extension to flat Lambda cold dark matter, we expect to measure H-0 to <3.5 per cent in most models, spatial curvature Omega(k) to 0.004, w to 0.14 and the effective number of neutrino species to 0.2 (1s uncertainties) when combined with current cosmic microwave background (CMB) experiments. These are, respectively, a factor of similar to 15, similar to 2 and similar to 1.5 tighter than CMB alone. Our data set will further enable us to study the stellar initial mass function of the lens galaxies, and the co-evolution of supermassive black holes and their host galaxies. This program will provide a foundation for extracting cosmological distances from the hundreds of time-delay lenses that are expected to be discovered in current and future surveys.

H0LiCOW – IV. Lens mass model of HE 0435−1223 and blind measurement of its time-delay distance for cosmology

Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the Hubble constant, H-0. We present a blind lens model analysis of the quadruply imaged quasar lens HE 0435-1223 using deep Hubble Space Telescope imaging, updated time-delay measurements from the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL), a measurement of the velocity dispersion of the lens galaxy based on Keck data, and a characterization of the mass distribution along the line of sight. HE 0435-1223 is the third lens analysed as a part of the H-0 Lenses in COSMOGRAILs Wellspring (HOLiCOW) project. We account for various sources of systematic uncertainty, including the detailed treatment of nearby perturbers, the parametrization of the galaxy light and mass profile, and the regions used for lens modelling. We constrain the effective time delay distance to be D-Delta t = 2612(191)(+208) Mpc, a precision of 7.6 per cent. From HE 0435-1223 alone, we infer a Hubble constant of H-0 = 73.1(6.0)(+5.7) km s(-1) Mpc(-1) assuming a flat ACDM cosmology. The cosmographic inference based on the three lenses analysed by HOLiCOW to date is presented in a companion paper (HOLiCOW Paper V).

PRIMUS: The Relationship between Star Formation and AGN Accretion

We study the evidence for a connection between active galactic nuclei (AGN) fueling and star formation by investigating the relationship between the X-ray luminosities of AGN and the star formation rates (SFRs) of their host galaxies. We identify a sample of 309 AGN with

PRIMUS: GALAXY CLUSTERING AS A FUNCTION OF LUMINOSITY AND COLOR AT 0.2 <z< 1

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A new hybrid framework to efficiently model lines of sight to gravitational lenses

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PRIMUS: An Observationally Motivated Model to Connect the Evolution of the Active Galactic Nucleus and Galaxy Populations out to z ~ 1

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PRIMUS: ENHANCED SPECIFIC STAR FORMATION RATES IN CLOSE GALAXY PAIRS

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