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The environmental dependence of H I in galaxies in the EAGLE simulations.

Marasco, A. and Crain, R. A. and Schaye, J. and Bahé, Y. M. and van der Hulst, T. and Theuns, T. and Bower, R. G. (2016) 'The environmental dependence of H I in galaxies in the EAGLE simulations.', Monthly notices of the Royal Astronomical Society., 461 (3). pp. 2630-2649.


We use the EAGLE suite of cosmological hydrodynamical simulations to study how the H I content of present-day galaxies depends on their environment. We show that EAGLE reproduces observed H I mass–environment trends very well, while semi-analytic models typically overpredict the average H I masses in dense environments. The environmental processes act primarily as an on/off switch for the H I content of satellites with M* > 109 M⊙. At a fixed M*, the fraction of H I-depleted satellites increase with increasing host halo mass M200 in response to stronger environmental effects, while at a fixed M200 it decreases with increasing satellite M* as the gas is confined by deeper gravitational potentials. H I-depleted satellites reside mostly, but not exclusively, within the virial radius r200 of their host halo. We investigate the origin of these trends by focusing on three environmental mechanisms: ram pressure stripping by the intragroup medium, tidal stripping by the host halo and satellite–satellite encounters. By tracking back in time the evolution of the H I-depleted satellites, we find that the most common cause of H I removal is satellite encounters. The time-scale for H I removal is typically less than 0.5 Gyr. Tidal stripping occurs in haloes of M200 < 1014 M⊙ within 0.5 × r200, while the other processes act also in more massive haloes, generally within r200. Conversely, we find that ram pressure stripping is the most common mechanism that disturbs the H I morphology of galaxies at redshift z = 0. This implies that H I removal due to satellite–satellite interactions occurs on shorter time-scales than the other processes.

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Publisher statement:This article has been published in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:18 June 2016
Date deposited:06 October 2016
Date of first online publication:24 June 2016
Date first made open access:06 October 2016

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