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Neutral CGM as damped Ly α absorbers at high redshift

Stern, Jonathan and Sternberg, Amiel and Faucher-Giguère, Claude-André and Hafen, Zachary and Fielding, Drummond and Quataert, Eliot and Wetzel, Andrew and Anglés-Alcázar, Daniel and El-Badry, Kareem and Kereš, Dušan and Hopkins, Philip F. (2021) Neutral CGM as damped Ly α absorbers at high redshift. Monthly Notices of the Royal Astronomical Society, 507 (2). pp. 2869-2884. ISSN 0035-8711. doi:10.1093/mnras/stab2240.

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Recent searches for the hosts of z ∼ 4 damped Ly α absorbers (DLAs) have detected bright galaxies at distances of tens of kpc from the DLA. Using the FIRE-2 cosmological zoom simulations, we argue that these relatively large distances are due to a predominantly cool and neutral inner circumgalactic medium (CGM) surrounding high-redshift galaxies. The inner CGM is cool because of the short cooling time of hot gas in ≲10¹² M_⊙ haloes, which implies that accretion and feedback energy are radiated quickly, while it is neutral due to high volume densities and column densities at high redshift that shield cool gas from photoionization. Our analysis predicts large DLA covering factors (⁠≳50 per cent) out to impact parameters ∼0.3[(1 + z)/5]^(3/2) R_(vir) from the central galaxies at z ≳ 1, equivalent to a proper distance of ∼21 M^(1/3)₁₂((1+z)/5)^(1/2) kpc (R_(vir) and M₁₂ are the halo virial radius and mass in units of 10¹² M_⊙⁠, respectively). This implies that DLA covering factors at z ∼ 4 may be comparable to unity out to a distance ∼10 times larger than stellar half-mass radii. A predominantly neutral inner CGM in the early universe suggests that its mass and metallicity can be directly constrained by absorption surveys, without resorting to the large ionization corrections as required for ionized CGM.

Item Type:Article
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URLURL TypeDescription Paper ItemGIZMO Code ItemFIRE project
Stern, Jonathan0000-0002-7541-9565
Sternberg, Amiel0000-0001-5065-9530
Faucher-Giguère, Claude-André0000-0002-4900-6628
Hafen, Zachary0000-0001-7326-1736
Fielding, Drummond0000-0003-3806-8548
Quataert, Eliot0000-0001-9185-5044
Wetzel, Andrew0000-0003-0603-8942
Anglés-Alcázar, Daniel0000-0001-5769-4945
El-Badry, Kareem0000-0002-6871-1752
Kereš, Dušan0000-0002-1666-7067
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 July 30. Received 2021 July 30; in original form 2021 March 9. Published: 20 August 2021. We thank the anonymous referee for insightful comments that substantially improved the paper. We thank F. Holguin and C. Hayward for conducting the radiation transfer analysis described in Section 6.4. JS is supported by the CIERA Postdoctoral Fellowship Program. This research was also supported by the German Science Foundation via DIP grant STE 1869/2-1 GE 625/17-1 at Tel Aviv University. CAFG was supported by NSF through grants AST-1715216 and CAREER award AST-1652522; by NASA through grant 17-ATP17-0067; by STScI through grant HST-AR-16124.001-A; and by a Cottrell Scholar Award and a Scialog Award from the Research Corporation for Science Advancement. DAA acknowledges support by NSF grant AST-2009687 and by the Flatiron Institute, which is supported by the Simons Foundation. AW received support from NASA through ATP grants 80NSSC18K1097 and 80NSSC20K0513; HST grants GO-14734, AR-15057, AR-15809, and GO-15902 from STScI; a Scialog Award from the Heising-Simons Foundation; and a Hellman Fellowship. Data Availability: The data supporting the plots within this article are available on reasonable request to the corresponding author. A public version of the GIZMO code is available at∼phopkins/Site/GIZMO.html. Additional data including simulation snapshots, initial conditions, and derived data products are available at
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)STE 1869/2-1 GE 625/17-1
Cottrell Scholar of Research CorporationUNSPECIFIED
Flatiron InstituteUNSPECIFIED
Simons FoundationUNSPECIFIED
NASA Hubble FellowshipGO-14734
NASA Hubble FellowshipAR-15057
NASA Hubble FellowshipAR-15809
NASA Hubble FellowshipGO-15902
Heising-Simons FoundationUNSPECIFIED
Hellman FellowshipUNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: high-redshift – quasars: absorption lines
Issue or Number:2
Record Number:CaltechAUTHORS:20211104-211055622
Persistent URL:
Official Citation:Jonathan Stern, Amiel Sternberg, Claude-André Faucher-Giguère, Zachary Hafen, Drummond Fielding, Eliot Quataert, Andrew Wetzel, Daniel Anglés-Alcázar, Kareem El-Badry, Dušan Kereš, Philip F Hopkins, Neutral CGM as damped Ly α absorbers at high redshift, Monthly Notices of the Royal Astronomical Society, Volume 507, Issue 2, October 2021, Pages 2869–2884,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111754
Deposited By: Tony Diaz
Deposited On:05 Nov 2021 19:33
Last Modified:05 Jan 2023 23:06

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