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Title: THE GASEOUS ENVIRONMENT OF HIGH-z GALAXIES: PRECISION MEASUREMENTS OF NEUTRAL HYDROGEN IN THE CIRCUMGALACTIC MEDIUM OF z {approx} 2-3 GALAXIES IN THE KECK BARYONIC STRUCTURE SURVEY

Abstract

We present results from the Keck Baryonic Structure Survey (KBSS), a unique spectroscopic survey of the distant universe designed to explore the details of the connection between galaxies and intergalactic baryons within the same survey volumes, focusing particularly on scales from {approx}50 kpc to a few Mpc. The KBSS is optimized for the redshift range z {approx} 2-3, combining S/N {approx}100 Keck/HIRES spectra of 15 of the brightest QSOs in the sky at z {approx_equal} 2.5-2.9 with very densely sampled galaxy redshift surveys within a few arcmin of each QSO sightline. In this paper, we present quantitative results on the distribution, column density, kinematics, and absorber line widths of neutral hydrogen (H I) surrounding a subset of 886 KBSS star-forming galaxies with 2.0 {approx}< z {approx}< 2.8 and with projected distances {<=}3 physical Mpc from a QSO sightline. Using Voigt profile decompositions of the full Ly{alpha} forest region of all 15 QSO spectra, we compiled a catalog of {approx}6000 individual absorbers in the redshift range of interest, with 12 {<=} log (N{sub HI}) {<=}21. These are used to measure H I absorption statistics near the redshifts of foreground galaxies as a function of projected galactocentric distance from the QSO sightlinemore » and for randomly chosen locations in the intergalactic medium (IGM) within the survey volume. We find that N{sub HI} and the multiplicity of velocity-associated H I components increase rapidly with decreasing galactocentric impact parameter and as the systemic redshift of the galaxy is approached. The strongest H I absorbers within {approx_equal} 100 physical kpc of galaxies have N{sub HI} {approx}3 orders of magnitude higher than those near random locations in the IGM. The circumgalactic zone of most significantly enhanced H I absorption is found within transverse distances of {approx}< 300 kpc and within {+-}300 km s{sup -1} of galaxy systemic redshifts. Taking this region as the defining bounds of the circumgalactic medium (CGM), nearly half of absorbers with log(N{sub HI}) > 15.5 are found within the CGM of galaxies meeting our photometric selection criteria, while their CGM occupy only 1.5% of the cosmic volume. The spatial covering fraction, multiplicity of absorption components, and characteristic N{sub HI} remain significantly elevated to transverse distances of {approx}2 physical Mpc from galaxies in our sample. Absorbers with N{sub HI} >10{sup 14.5} cm{sup -2} are tightly correlated with the positions of galaxies, while absorbers with lower N{sub HI} are correlated with galaxy positions only on {approx}>Mpc scales. Redshift anisotropies on these larger scales indicate coherent infall toward galaxy locations, while on scales of {approx}100 physical kpc peculiar velocities of {Delta}v {approx_equal} {+-}260 km s{sup -1} with respect to the galaxies are indicated. The median Doppler widths of individual absorbers within 1-3 r{sub vir} of galaxies are larger by {approx_equal} 50% than randomly chosen absorbers of the same N{sub HI}, suggesting higher gas temperatures and/or increased turbulence likely caused by some combination of accretion shocks and galactic winds around galaxies with M{sub halo} {approx_equal} 10{sup 12} M{sub Sun} at z {approx} 2-3.« less

Authors:
; ;  [1];  [2];  [3];  [4];  [5];  [6];  [7]
  1. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States)
  2. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
  3. Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)
  4. Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  5. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
  6. Department of Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90024 (United States)
  7. Department of Physics, University of Wisconsin Milwaukee, Milwaukee, WI 53211 (United States)
Publication Date:
OSTI Identifier:
22034550
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 750; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTRA; ACCURACY; ANISOTROPY; ASTROPHYSICS; BARYONS; CATALOGS; COSMOLOGY; DISTANCE; EMISSION SPECTRA; GALACTIC EVOLUTION; GALAXIES; HYDROGEN; IMPACT PARAMETER; LINE WIDTHS; MULTIPLICITY; QUASARS; RED SHIFT; TURBULENCE; UNIVERSE

Citation Formats

Rudie, Gwen C, Steidel, Charles C, Trainor, Ryan F, Rakic, Olivera, Bogosavljevic, Milan, Pettini, Max, Reddy, Naveen, Shapley, Alice E, Erb, Dawn K, and Law, David R., E-mail: gwen@astro.caltech.edu. THE GASEOUS ENVIRONMENT OF HIGH-z GALAXIES: PRECISION MEASUREMENTS OF NEUTRAL HYDROGEN IN THE CIRCUMGALACTIC MEDIUM OF z {approx} 2-3 GALAXIES IN THE KECK BARYONIC STRUCTURE SURVEY. United States: N. p., 2012. Web. doi:10.1088/0004-637X/750/1/67.
Rudie, Gwen C, Steidel, Charles C, Trainor, Ryan F, Rakic, Olivera, Bogosavljevic, Milan, Pettini, Max, Reddy, Naveen, Shapley, Alice E, Erb, Dawn K, & Law, David R., E-mail: gwen@astro.caltech.edu. THE GASEOUS ENVIRONMENT OF HIGH-z GALAXIES: PRECISION MEASUREMENTS OF NEUTRAL HYDROGEN IN THE CIRCUMGALACTIC MEDIUM OF z {approx} 2-3 GALAXIES IN THE KECK BARYONIC STRUCTURE SURVEY. United States. https://doi.org/10.1088/0004-637X/750/1/67
Rudie, Gwen C, Steidel, Charles C, Trainor, Ryan F, Rakic, Olivera, Bogosavljevic, Milan, Pettini, Max, Reddy, Naveen, Shapley, Alice E, Erb, Dawn K, and Law, David R., E-mail: gwen@astro.caltech.edu. Tue . "THE GASEOUS ENVIRONMENT OF HIGH-z GALAXIES: PRECISION MEASUREMENTS OF NEUTRAL HYDROGEN IN THE CIRCUMGALACTIC MEDIUM OF z {approx} 2-3 GALAXIES IN THE KECK BARYONIC STRUCTURE SURVEY". United States. https://doi.org/10.1088/0004-637X/750/1/67.
@article{osti_22034550,
title = {THE GASEOUS ENVIRONMENT OF HIGH-z GALAXIES: PRECISION MEASUREMENTS OF NEUTRAL HYDROGEN IN THE CIRCUMGALACTIC MEDIUM OF z {approx} 2-3 GALAXIES IN THE KECK BARYONIC STRUCTURE SURVEY},
author = {Rudie, Gwen C and Steidel, Charles C and Trainor, Ryan F and Rakic, Olivera and Bogosavljevic, Milan and Pettini, Max and Reddy, Naveen and Shapley, Alice E and Erb, Dawn K and Law, David R., E-mail: gwen@astro.caltech.edu},
abstractNote = {We present results from the Keck Baryonic Structure Survey (KBSS), a unique spectroscopic survey of the distant universe designed to explore the details of the connection between galaxies and intergalactic baryons within the same survey volumes, focusing particularly on scales from {approx}50 kpc to a few Mpc. The KBSS is optimized for the redshift range z {approx} 2-3, combining S/N {approx}100 Keck/HIRES spectra of 15 of the brightest QSOs in the sky at z {approx_equal} 2.5-2.9 with very densely sampled galaxy redshift surveys within a few arcmin of each QSO sightline. In this paper, we present quantitative results on the distribution, column density, kinematics, and absorber line widths of neutral hydrogen (H I) surrounding a subset of 886 KBSS star-forming galaxies with 2.0 {approx}< z {approx}< 2.8 and with projected distances {<=}3 physical Mpc from a QSO sightline. Using Voigt profile decompositions of the full Ly{alpha} forest region of all 15 QSO spectra, we compiled a catalog of {approx}6000 individual absorbers in the redshift range of interest, with 12 {<=} log (N{sub HI}) {<=}21. These are used to measure H I absorption statistics near the redshifts of foreground galaxies as a function of projected galactocentric distance from the QSO sightline and for randomly chosen locations in the intergalactic medium (IGM) within the survey volume. We find that N{sub HI} and the multiplicity of velocity-associated H I components increase rapidly with decreasing galactocentric impact parameter and as the systemic redshift of the galaxy is approached. The strongest H I absorbers within {approx_equal} 100 physical kpc of galaxies have N{sub HI} {approx}3 orders of magnitude higher than those near random locations in the IGM. The circumgalactic zone of most significantly enhanced H I absorption is found within transverse distances of {approx}< 300 kpc and within {+-}300 km s{sup -1} of galaxy systemic redshifts. Taking this region as the defining bounds of the circumgalactic medium (CGM), nearly half of absorbers with log(N{sub HI}) > 15.5 are found within the CGM of galaxies meeting our photometric selection criteria, while their CGM occupy only 1.5% of the cosmic volume. The spatial covering fraction, multiplicity of absorption components, and characteristic N{sub HI} remain significantly elevated to transverse distances of {approx}2 physical Mpc from galaxies in our sample. Absorbers with N{sub HI} >10{sup 14.5} cm{sup -2} are tightly correlated with the positions of galaxies, while absorbers with lower N{sub HI} are correlated with galaxy positions only on {approx}>Mpc scales. Redshift anisotropies on these larger scales indicate coherent infall toward galaxy locations, while on scales of {approx}100 physical kpc peculiar velocities of {Delta}v {approx_equal} {+-}260 km s{sup -1} with respect to the galaxies are indicated. The median Doppler widths of individual absorbers within 1-3 r{sub vir} of galaxies are larger by {approx_equal} 50% than randomly chosen absorbers of the same N{sub HI}, suggesting higher gas temperatures and/or increased turbulence likely caused by some combination of accretion shocks and galactic winds around galaxies with M{sub halo} {approx_equal} 10{sup 12} M{sub Sun} at z {approx} 2-3.},
doi = {10.1088/0004-637X/750/1/67},
url = {https://www.osti.gov/biblio/22034550}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 750,
place = {United States},
year = {2012},
month = {5}
}