The Bimodal Absorption System Imaging Campaign (BASIC). I. A Dual Population of Low-metallicity Absorbers at z < 1

Michelle A. Berg; Nicolas Lehner; J. Christopher Howk; John M. O’Meara; Joop Schaye; Lorrie A. Straka; Kathy L. Cooksey; Todd M. Tripp; J. Xavier Prochaska; Benjamin D. Oppenheimer; Sean D. Johnson; Sowgat Muzahid; Rongmon Bordoloi; Jessica K. Werk; Andrew J. Fox; Neal Katz; Martin Wendt; Molly S. Peeples; Joseph Ribaudo; Jason Tumlinson

doi:10.3847/1538-4357/acb047

The Astrophysical Journal (Jan 2023)

The Bimodal Absorption System Imaging Campaign (BASIC). I. A Dual Population of Low-metallicity Absorbers at z < 1

Michelle A. Berg,
Nicolas Lehner,
J. Christopher Howk,
John M. O’Meara,
Joop Schaye,
Lorrie A. Straka,
Kathy L. Cooksey,
Todd M. Tripp,
J. Xavier Prochaska,
Benjamin D. Oppenheimer,
Sean D. Johnson,
Sowgat Muzahid,
Rongmon Bordoloi,
Jessica K. Werk,
Andrew J. Fox,
Neal Katz,
Martin Wendt,
Molly S. Peeples,
Joseph Ribaudo,
Jason Tumlinson

Affiliations

Michelle A. Berg: ORCiD; Department of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USA ; [email protected]; Department of Astronomy, The University of Texas at Austin , Austin, TX 78712, USA
Nicolas Lehner: ORCiD; Department of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USA ; [email protected]
J. Christopher Howk: ORCiD; Department of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USA ; [email protected]
John M. O’Meara: ORCiD; W.M. Keck Observatory 65-1120 Mamalahoa Highway, Kamuela, HI 96743, USA
Joop Schaye: ORCiD; Leiden Observatory, Leiden University , P.O. Box 9513, 2300 RA, Leiden, The Netherlands
Lorrie A. Straka: ORCiD; Leiden Observatory, Leiden University , P.O. Box 9513, 2300 RA, Leiden, The Netherlands
Kathy L. Cooksey: ORCiD; Department of Physics & Astronomy, University of Hawai‘i at Hilo , Hilo, HI 96720, USA
Todd M. Tripp: ORCiD; Department of Astronomy, University of Massachusetts , 710 North Pleasant Street, Amherst, MA 01003-9305, USA
J. Xavier Prochaska: ORCiD; Department of Astronomy and Astrophysics, University of California , Santa Cruz, CA 95064, USA; Kavli Institute for the Physics and Mathematics of the Universe (WIP) , 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Japan
Benjamin D. Oppenheimer: ORCiD; CASA, Department of Astrophysical and Planetary Sciences, University of Colorado , 389 UCB, Boulder, CO 80309, USA
Sean D. Johnson: ORCiD; Department of Astronomy, University of Michigan , Ann Arbor, MI 48109, USA
Sowgat Muzahid: ORCiD; IUCAA , Post Bag 04, Ganeshkhind, Pune-411007, India; Leibniz-Institute for Astrophysics Potsdam (AIP) , An der Sternwarte 16, D-14482 Potsdam, Germany
Rongmon Bordoloi: ORCiD; Department of Physics, North Carolina State University , 2401 Stinson Drive, Raleigh, NC 27695, USA
Jessica K. Werk: ORCiD; Department of Astronomy, University of Washington , Box 351580, Seattle, WA 98195, USA
Andrew J. Fox: ORCiD; AURA for ESA, Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Neal Katz: ORCiD; Department of Astronomy, University of Massachusetts , 710 North Pleasant Street, Amherst, MA 01003-9305, USA
Martin Wendt: ORCiD; Leibniz-Institute for Astrophysics Potsdam (AIP) , An der Sternwarte 16, D-14482 Potsdam, Germany; Institut für Physik und Astronomie, Universität Potsdam , Karl-Liebknecht-Str 24/25, D-14476 Golm, Germany
Molly S. Peeples: ORCiD; Space Telescope Science Institute , Baltimore, MD 21218, USA; Department of Physics and Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA
Joseph Ribaudo: ORCiD; Department of Engineering and Physics, Providence College , Providence, RI 02918, USA
Jason Tumlinson: ORCiD; Space Telescope Science Institute , Baltimore, MD 21218, USA; Department of Physics and Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA

DOI: https://doi.org/10.3847/1538-4357/acb047
Journal volume & issue: Vol. 944, no. 1
p. 101

Abstract

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The bimodal absorption system imaging campaign (BASIC) aims to characterize the galaxy environments of a sample of 36 H i -selected partial Lyman limit systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields at z ≲ 1. These pLLSs/LLSs provide a unique sample of absorbers with unbiased and well-constrained metallicities, allowing us to explore the origins of metal-rich and low-metallicity circumgalactic medium (CGM) at z < 1. Here we present Keck/KCWI and Very Large Telescope/MUSE observations of 11 of these QSO fields (19 pLLSs) that we combine with Hubble Space Telescope/Advanced Camera for Surveys imaging to identify and characterize the absorber-associated galaxies at 0.16 ≲ z ≲ 0.84. We find 23 unique absorber-associated galaxies, with an average of one associated galaxy per absorber. For seven absorbers, all with <10% solar metallicities, we find no associated galaxies with $\mathrm{log}{M}_{\star }\gtrsim 9.0$ within ρ / R _vir and ∣Δ v ∣/ v _esc ≤ 1.5 with respect to the absorber. We do not find any strong correlations between the metallicities or H i column densities of the gas and most of the galaxy properties, except for the stellar mass of the galaxies: the low-metallicity ([X/H] ≤ −1.4) systems have a probability of ${0.39}_{-0.15}^{+0.16}$ for having a host galaxy with $\mathrm{log}{M}_{\star }\geqslant 9.0$ within ρ / R _vir ≤ 1.5, while the higher metallicity absorbers have a probability of ${0.78}_{-0.13}^{+0.10}$ . This implies metal-enriched pLLSs/LLSs at z < 1 are typically associated with the CGM of galaxies with $\mathrm{log}{M}_{\star }\gt 9.0$ , whereas low-metallicity pLLSs/LLSs are found in more diverse locations, with one population arising in the CGM of galaxies and another more broadly distributed in overdense regions of the universe. Using absorbers not associated with galaxies, we estimate the unweighted geometric mean metallicity of the intergalactic medium to be [X/H] ≲ −2.1 at z < 1, which is lower than previously estimated.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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