Why does the environmental influence on group and cluster galaxies extend beyond the virial radius

By Yannick Bahé, Ian G. McCarthy, M. Balogh, Andreea S. Font Institute of Astronomy, Cambridge, S. O. Physics, Astronomy, Birmingham, D. Physics, Waterloo. 2012

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In the local Universe, galaxies in groups and clusters contain less gas and are less likely to be forming stars than their field counterparts. This effect is not limited to the central group/cluster regions, but is shown by recent observations to persist out to several virial radii. To gain insight into the extent and cause of this large-scale environmental influence, we use a suite of high-resolution cosmological hydrodynamic simulations to analyse galaxies around simulated groups and clusters of a wide range of mass (log10 Mhost/M⊙ = [13.0, 15.2]). In qualitative agreement with the observations, we find a systematic depletion of both hot and cold gas and a decline in the star forming fraction of galaxies as far out as ∼ 5 r200 from the host centre. A substantial fraction of these galaxies are on highly elliptical orbits and are not infalling for the first time (∼ 50 per cent at 2 r200, independent of host mass) or are affected by ‘preprocessing’ (less than 10 per cent of galaxies around groups, increasing to ∼ 50 per cent near a massive cluster), even a combination of these indirect mechanisms does not fully account for the environmental influence, particularly in the case of the hot gas content. Direct ram pressure interaction with an extended gas ‘halo’ surrounding groups and clusters is shown to be sufficiently strong to strip the hot gas atmospheres of infalling galaxies out to ∼ 5 r200. We show that this influence is highly anisotropic, with ram pressure along filaments enhanced by up to a factor of 100 despite significant co-flow of gas and galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/b4ee766213391b66e3986b045f0536c5ae71e289

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Citations in the corpus

BUDHIES II: a phase-space view of H i gas stripping and star formation quenching in cluster galaxies (2015, background): “Leaving aside the phase-space view for a moment, and only concentrating on r/R200, we get the trends shown in Figure 8, that can be compared with those found by Bahé et al. (2013).”
Quenching and ram pressure stripping of simulated Milky Way satellite galaxies (2017, background): “Bahé et al. (2013) found environmental quenching around hosts above 1013 M in mass out to 5R200.”
LoCuSS: THE SLOW QUENCHING OF STAR FORMATION IN CLUSTER GALAXIES AND THE NEED FOR PRE-PROCESSING (2015, background): “This process may be effective well beyond the virial radius, with the extended gaseous halo of clusters remaining hot (106 K) and sufficiently dense to strip the hot gas atmospheres of infalling galaxies out to ∼5r200 (Bahé et al. 2013; Gabor & Davé 2015).”