The Cosmic Ultraviolet Baryon Survey (CUBS) – I. Overview and the diverse environments of Lyman limit systems at z < 1. Issue 1 (17th June 2020)

• Record Type: Journal Article
• Authors: Chen, Hsiao-Wen; Zahedy, Fakhri S; Boettcher, Erin; Cooper, Thomas M; Johnson, Sean D; Rudie, Gwen C; Chen, Mandy C; Walth, Gregory L; Cantalupo, Sebastiano; Cooksey, Kathy L; Faucher-Giguère, Claude-André; Greene, Jenny E; Lopez, Sebastian; Mulchaey, John S; Penton, Steven V; Petitjean, Patrick; Putman, Mary E; Rafelski, Marc; Rauch, Michael; Schaye, Joop; Simcoe, Robert A; Weiner, Benjamin J
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 497:Issue 1(2020)
• Page Start: 498
• Page End: 520
• Publication Date: 2020-06-17
• Subjects: surveys -- galaxies: evolution -- galaxies: haloes -- quasars: absorption lines; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa1773
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present initial results from the Cosmic Ultraviolet Baryon Survey (CUBS). CUBS is designed to map diffuse baryonic structures at redshift z ≲ 1 using absorption-line spectroscopy of 15 UV-bright QSOs with matching deep galaxy survey data. CUBS QSOs are selected based on their NUV brightness to avoid biases against the presence of intervening Lyman limit systems (LLSs) at z abs &lt; 1. We report five new LLSs of $\log \, N({\mathrm{ H} \, {\small I}})/{{\rm cm^{-2}}}\gtrsim 17.2$ over a total redshift survey path-length of $\Delta \, z_{\mathrm{ LL}}=9.3$, and a number density of $n(z)=0.43_{-0.18}^{+0.26}$ . Considering all absorbers with $\log \, N({{\mathrm{ H} \, {\small I}}})/{{\rm cm^{-2}}}\gt 16.5$ leads to $n(z)=1.08_{-0.25}^{+0.31}$ at z abs &lt; 1. All LLSs exhibit a multicomponent structure and associated metal transitions from multiple ionization states such as C ii, C iii, Mg ii, Si ii, Si iii, and O vi absorption. Differential chemical enrichment levels as well as ionization states are directly observed across individual components in three LLSs. We present deep galaxy survey data obtained using the VLT-MUSE integral field spectrograph and the Magellan Telescopes, reaching sensitivities necessary for detecting galaxies fainter than $0.1\, L_*$ at d ≲ 300 physical kpc (pkpc) in all five fields. A diverse range of galaxy properties is seen around these LLSs, from a low-mass dwarf galaxy pair, a co-rotating gaseous halo/disc, a star-forming galaxy, a massive quiescent galaxy, to a galaxy group. The closest galaxies have projected distances ranging from d = 15 to 72 pkpc and intrinsic luminosities from ${\approx} 0.01\, L_*$ to ${\approx} 3\, L_*$ . Our study shows that LLSs originate in a variety of galaxy environments and trace gaseous structures with a broad range of metallicities.