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

Bahe, YM and McCarthy, IG and Balogh, ML and Font, AS (2013) Why does the environmental influence on group and cluster galaxies extend beyond the virial radius? MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 430 (4). pp. 3017-3031. ISSN 0035-8711

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Abstract

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.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Bahé, Y. M. et Al. (2013)Why does the environmental influence on group and cluster galaxies extend beyond the virial radius? is available online at: http://dx.doi.org/10.1093/mnras/stt109
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: OXFORD UNIV PRESS
Related URLs:
Date Deposited: 30 Jun 2015 13:24
Last Modified: 30 Jun 2015 13:24
DOI or Identification number: /10.1093/mnras/stt109
URI: http://researchonline.ljmu.ac.uk/id/eprint/1469

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