The diversity of the circumgalactic medium around z = 0 Milky Way-mass galaxies from the Auriga simulations

Hani, MH, Ellison, SL, Sparre, M, Grand, RJJ ORCID: 0000-0001-9667-1340, Pakmor, R, Gomez, FA and Springel, V (2019) The diversity of the circumgalactic medium around z = 0 Milky Way-mass galaxies from the Auriga simulations. Monthly Notices of the Royal Astronomical Society, 488 (1). pp. 135-152. ISSN 0035-8711

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Abstract

Galaxies are surrounded by massive gas reservoirs (i.e. the circumgalactic medium; CGM) which play a key role in their evolution. The properties of the CGM, which are dependent on a variety of internal and environmental factors, are often inferred from absorption line surveys which rely on a limited number of single lines-of-sight. In this work we present an analysis of 28 galaxy haloes selected from the Auriga project, a cosmological magnetohydrodynamical zoom-in simulation suite of isolated Milky Way-mass galaxies, to understand the impact of CGM diversity on observational studies. Although the Auriga haloes are selected to populate a narrow range in halo mass, our work demonstrates that the CGM of L galaxies is extremely diverse: column densities of commonly observed species span ∼3 − 4 dex and their covering fractions range from ∼5 to 90 per cent. Despite this diversity, we identify the following correlations: 1) the covering fractions (CF) of hydrogen and metals of the Auriga haloes positively correlate with stellar mass, 2) the CF of H I, C IV, and Si II anticorrelate with active galactic nucleus luminosity due to ionization effects, and 3) the CF of H I, C IV, and Si II positively correlate with galaxy disc fraction due to outflows populating the CGM with cool and dense gas. The Auriga sample demonstrates striking diversity within the CGM of L galaxies, which poses a challenge for observations reconstructing CGM characteristics from limited samples, and also indicates that long-term merger assembly history and recent star formation are not the dominant sculptors of the CGM.

Item Type:	Article
Additional Information:	This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press (OUP)
Date of acceptance:	17 June 2019
Date of first compliant Open Access:	19 April 2023
Date Deposited:	19 Apr 2023 11:53
Last Modified:	05 Jul 2025 08:45
DOI or ID number:	10.1093/mnras/stz1708
URI:	https://researchonline.ljmu.ac.uk/id/eprint/19320

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