Predictions for the angular dependence of gas mass flow rate and metallicity in the circumgalactic medium
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2009.07809.pdf
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Accepted version
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Author(s)
Péroux, Céline
Nelson, Dylan
van de Voort, Freeke
Pillepich, Annalisa
Marinacci, Federico
Vogelsberger, Mark
Hernquist, Lars
Date Issued
September 2020
Journal
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Citation
Péroux, Céline et al. "Predictions for the angular dependence of gas mass flow rate and metallicity in the circumgalactic medium." Monthly Notices of the Royal Astronomical Society 499, 2 (September 2020): 2462–2473 © 2020 The Author(s)
Version
Author's final manuscript
Abstract
We use cosmological hydrodynamical simulations to examine the physical properties of the gas in the circumgalactic media (CGM) of star-forming galaxies as a function of angular orientation. We utilize TNG50 of the IllustrisTNG project, as well as the EAGLE simulation to show that observable properties of CGM gas correlate with azimuthal angle, defined as the galiocentric angle with respect to the central galaxy. Both simulations are in remarkable agreement in predicting a strong modulation of flow rate direction with azimuthal angle: inflow is more substantial along the galaxy major axis, while outflow is strongest along the minor axis. The absolute rates are noticeably larger for higher log (M[subscript star]/ M[subscript ⨀] ~10.5) stellar mass galaxies, up to an order of magnitude compared to [M with dot above] ≲1 M[subscript ⨀] yr[superscript −1]sr[superscript −1] for log(M[subscript star]/ M[subscript ⨀] ~ 9.5) objects. Notwithstanding the different numerical and physical models, both TNG50 and EAGLE predict that the average metallicity of the CGM is higher along the minor versus major axes of galaxies. The angular signal is robust across a wide range of galaxy stellar mass 8.5 < (M[subscript star]/ M[subscript ⨀]) < 10.5 at z < 1. This azimuthal dependence is particularly clear at larger impact parameters b ≥ 100 kpc. Our results present a global picture, whereby despite the numerous mixing processes, there is a clear angular dependence of the CGM metallicity. We make forecasts for future large survey programmes that will be able to compare against these expectations. Indeed, characterizing the kinematics, spatial distribution and metal content of CGM gas is key to a full understanding of the exchange of mass, metals, and energy between galaxies and their surrounding environments.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1093/mnras/staa2888
