The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z
<jats:title>ABSTRACT</jats:title> <jats:p>We present a systematic investigation of physical conditions and elemental abundances in four optically thick Lyman-limit systems (LLSs) at z = 0.36–0.6 discovered within the Cosmic Ultraviolet Baryon Survey (CUBS). Because...
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Oxford University Press (OUP)
2022
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Online Access: | https://hdl.handle.net/1721.1/142216 |
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author | Zahedy, Fakhri S Chen, Hsiao-Wen Cooper, Thomas M Boettcher, Erin Johnson, Sean D Rudie, Gwen C Chen, Mandy C 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 Walth, Gregory L |
author2 | MIT Kavli Institute for Astrophysics and Space Research |
author_facet | MIT Kavli Institute for Astrophysics and Space Research Zahedy, Fakhri S Chen, Hsiao-Wen Cooper, Thomas M Boettcher, Erin Johnson, Sean D Rudie, Gwen C Chen, Mandy C 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 Walth, Gregory L |
author_sort | Zahedy, Fakhri S |
collection | MIT |
description | <jats:title>ABSTRACT</jats:title>
<jats:p>We present a systematic investigation of physical conditions and elemental abundances in four optically thick Lyman-limit systems (LLSs) at z = 0.36–0.6 discovered within the Cosmic Ultraviolet Baryon Survey (CUBS). Because intervening LLSs at z &lt; 1 suppress far-UV (ultraviolet) light from background QSOs, an unbiased search of these absorbers requires a near-UV-selected QSO sample, as achieved by CUBS. CUBS LLSs exhibit multicomponent kinematic structure and a complex mix of multiphase gas, with associated metal transitions from multiple ionization states such as C ii, C iii, N iii, Mg ii, Si ii, Si iii, O ii, O iii, O vi, and Fe ii absorption that span several hundred km s−1 in line-of-sight velocity. Specifically, higher column density components (log N(H i)/cm−2≳ 16) in all four absorbers comprise dynamically cool gas with $\langle T \rangle =(2\pm 1) \times 10^4\,$K and modest non-thermal broadening of $\langle b_\mathrm{nt} \rangle =5\pm 3\,$km s−1. The high quality of the QSO absorption spectra allows us to infer the physical conditions of the gas, using a detailed ionization modelling that takes into account the resolved component structures of H i and metal transitions. The range of inferred gas densities indicates that these absorbers consist of spatially compact clouds with a median line-of-sight thickness of $160^{+140}_{-50}$ pc. While obtaining robust metallicity constraints for the low density, highly ionized phase remains challenging due to the uncertain $N\mathrm{(H\, {\small I})}$, we demonstrate that the cool-phase gas in LLSs has a median metallicity of $\mathrm{[\alpha /H]_{1/2}}=-0.7^{+0.1}_{-0.2}$, with a 16–84 percentile range of [α/H] = (−1.3, −0.1). Furthermore, the wide range of inferred elemental abundance ratios ([C/α], [N/α], and [Fe/α]) indicate a diversity of chemical enrichment histories. Combining the absorption data with deep galaxy survey data characterizing the galaxy environment of these absorbers, we discuss the physical connection between star-forming regions in galaxies and diffuse gas associated with optically thick absorption systems in the z &lt; 1 circumgalactic medium.</jats:p> |
first_indexed | 2024-09-23T14:18:56Z |
format | Article |
id | mit-1721.1/142216 |
institution | Massachusetts Institute of Technology |
language | English |
last_indexed | 2024-09-23T14:18:56Z |
publishDate | 2022 |
publisher | Oxford University Press (OUP) |
record_format | dspace |
spelling | mit-1721.1/1422162023-12-07T18:04:31Z The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z Zahedy, Fakhri S Chen, Hsiao-Wen Cooper, Thomas M Boettcher, Erin Johnson, Sean D Rudie, Gwen C Chen, Mandy C 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 Walth, Gregory L MIT Kavli Institute for Astrophysics and Space Research <jats:title>ABSTRACT</jats:title> <jats:p>We present a systematic investigation of physical conditions and elemental abundances in four optically thick Lyman-limit systems (LLSs) at z = 0.36–0.6 discovered within the Cosmic Ultraviolet Baryon Survey (CUBS). Because intervening LLSs at z &lt; 1 suppress far-UV (ultraviolet) light from background QSOs, an unbiased search of these absorbers requires a near-UV-selected QSO sample, as achieved by CUBS. CUBS LLSs exhibit multicomponent kinematic structure and a complex mix of multiphase gas, with associated metal transitions from multiple ionization states such as C ii, C iii, N iii, Mg ii, Si ii, Si iii, O ii, O iii, O vi, and Fe ii absorption that span several hundred km s−1 in line-of-sight velocity. Specifically, higher column density components (log N(H i)/cm−2≳ 16) in all four absorbers comprise dynamically cool gas with $\langle T \rangle =(2\pm 1) \times 10^4\,$K and modest non-thermal broadening of $\langle b_\mathrm{nt} \rangle =5\pm 3\,$km s−1. The high quality of the QSO absorption spectra allows us to infer the physical conditions of the gas, using a detailed ionization modelling that takes into account the resolved component structures of H i and metal transitions. The range of inferred gas densities indicates that these absorbers consist of spatially compact clouds with a median line-of-sight thickness of $160^{+140}_{-50}$ pc. While obtaining robust metallicity constraints for the low density, highly ionized phase remains challenging due to the uncertain $N\mathrm{(H\, {\small I})}$, we demonstrate that the cool-phase gas in LLSs has a median metallicity of $\mathrm{[\alpha /H]_{1/2}}=-0.7^{+0.1}_{-0.2}$, with a 16–84 percentile range of [α/H] = (−1.3, −0.1). Furthermore, the wide range of inferred elemental abundance ratios ([C/α], [N/α], and [Fe/α]) indicate a diversity of chemical enrichment histories. Combining the absorption data with deep galaxy survey data characterizing the galaxy environment of these absorbers, we discuss the physical connection between star-forming regions in galaxies and diffuse gas associated with optically thick absorption systems in the z &lt; 1 circumgalactic medium.</jats:p> 2022-04-29T17:39:36Z 2022-04-29T17:39:36Z 2021 2022-04-29T17:35:02Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/142216 Zahedy, Fakhri S, Chen, Hsiao-Wen, Cooper, Thomas M, Boettcher, Erin, Johnson, Sean D et al. 2021. "The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z." Monthly Notices of the Royal Astronomical Society, 506 (1). en 10.1093/MNRAS/STAB1661 Monthly Notices of the Royal Astronomical Society Attribution-NonCommercial-ShareAlike 4.0 International https://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Oxford University Press (OUP) arXiv |
spellingShingle | Zahedy, Fakhri S Chen, Hsiao-Wen Cooper, Thomas M Boettcher, Erin Johnson, Sean D Rudie, Gwen C Chen, Mandy C 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 Walth, Gregory L The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z |
title | The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z |
title_full | The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z |
title_fullStr | The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z |
title_full_unstemmed | The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z |
title_short | The cosmic ultraviolet baryon survey (CUBS) – III. Physical properties and elemental abundances of Lyman-limit systems at z |
title_sort | cosmic ultraviolet baryon survey cubs iii physical properties and elemental abundances of lyman limit systems at z |
url | https://hdl.handle.net/1721.1/142216 |
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