Galaxy mergers moulding the circum-galactic medium

  • Galaxies are surrounded by sizeable gas reservoirs which host a significant amount of metals: the circum-galactic medium (CGM). The CGM acts as a mediator between the galaxy and the extragalactic medium. However, our understanding of how galaxy mergers, a major evolutionary transformation, impact the CGM remains deficient. We present a theoretical study of the effect of galaxy mergers on the CGM. We use hydrodynamical cosmological zoom-in simulations of a major merger selected from the Illustris project such that the z = 0 descendant has a halo mass and stellar mass comparable to the Milky Way. To study the CGM we then re-simulated this system at a 40 times better mass resolution, and included detailed post-processing ionization modelling. Our work demonstrates the effect the merger has on the characteristic size of the CGM, its metallicity, and the predicted covering fraction of various commonly observed gas-phase species, such as H I, C IV, and O VI. We show that merger-induced outflows can increase the CGM metallicity by 0.2-0.3Galaxies are surrounded by sizeable gas reservoirs which host a significant amount of metals: the circum-galactic medium (CGM). The CGM acts as a mediator between the galaxy and the extragalactic medium. However, our understanding of how galaxy mergers, a major evolutionary transformation, impact the CGM remains deficient. We present a theoretical study of the effect of galaxy mergers on the CGM. We use hydrodynamical cosmological zoom-in simulations of a major merger selected from the Illustris project such that the z = 0 descendant has a halo mass and stellar mass comparable to the Milky Way. To study the CGM we then re-simulated this system at a 40 times better mass resolution, and included detailed post-processing ionization modelling. Our work demonstrates the effect the merger has on the characteristic size of the CGM, its metallicity, and the predicted covering fraction of various commonly observed gas-phase species, such as H I, C IV, and O VI. We show that merger-induced outflows can increase the CGM metallicity by 0.2-0.3 dex within 0.5 Gyr post-merger. These effects last up to 6 Gyr post-merger. While the merger increases the total metal covering fractions by factors of 2-3, the covering fractions of commonly observed UV ions decrease due to the hard ionizing radiation from the active galactic nucleus, which we model explicitly. Our study of the single simulated major merger presented in this work demonstrates the significant impact that a galaxy interaction can have on the size, metallicity, and observed column densities of the CGM.show moreshow less

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Metadaten
Author details:Maan H. HaniORCiD, Martin SparreORCiDGND, Sara L. EllisonORCiD, Paul TorreyORCiD, Mark Vogelsberger
DOI:https://doi.org/10.1093/mnras/stx3252
ISSN:0035-8711
ISSN:1365-2966
Title of parent work (English):Monthly notices of the Royal Astronomical Society
Subtitle (English):I. The impact of a major merger
Publisher:Oxford Univ. Press
Place of publishing:Oxford
Publication type:Article
Language:English
Date of first publication:2017/12/20
Completion year:2017
Release date:2022/01/14
Tag:galaxies: evolution; galaxies: haloes; galaxies: interactions; methods: numerical
Volume:475
Issue:1
Number of pages:17
First page:1160
Last Page:1176
Funding institution:Institute for Theoretical Studies; MIT; NSERC Discovery GrantNatural Sciences and Engineering Research Council of Canada; NASA through Hubble FellowshipNational Aeronautics & Space Administration (NASA) [HST-HF2-51384.001-A]; STScISpace Telescope Science Institute; Association of Universities for Research in Astronomy, Inc., for NASA [NAS526555]; MIT RSC award; Alfred P. Sloan FoundationAlfred P. Sloan Foundation; NASA ATPNational Aeronautics & Space Administration (NASA) [NNX17AG29G]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
DDC classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Peer review:Referiert
Publishing method:Open Access / Bronze Open-Access
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