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Durham University

Department of Physics

Staff profile

Publication details for Prof Richard Bower

Marasco A. Crain R. A. Schaye J. Bahé Y. M. van der Hulst T. Theuns T. & 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): 2630-2649.

Author(s) from Durham


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.