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Star formation quenching in simulated group and cluster galaxies: When, how, and why?

Bahe, YM and McCarthy, IG (2015) Star formation quenching in simulated group and cluster galaxies: When, how, and why? Monthly Notices of the Royal Astronomical Society, 447. pp. 969-992. ISSN 0035-8711

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Star formation is observed to be suppressed in group and cluster galaxies compared to the field. To gain insight into the quenching process, we have analysed ~2000 galaxies formed in the GIMIC suite of cosmological hydrodynamical simulations. The time of quenching varies from ~2 Gyr before accretion (first crossing of r200,c) to >4 Gyr after, depending on satellite and host mass. Once begun, quenching is rapid (>~ 500 Myr) in low-mass galaxies (M* < 10^10 M_Sun), but significantly more protracted for more massive satellites. The simulations predict a substantial role of outflows driven by ram pressure -- but not tidal forces -- in removing the star-forming interstellar matter (ISM) from satellite galaxies, especially dwarfs (M* ~ 10^9 M_Sun) where they account for nearly two thirds of ISM loss in both groups and clusters. Immediately before quenching is complete, this fraction rises to ~80% even for Milky Way analogues (M* ~ 10^10.5 M_Sun) in groups (M_host ~ 10^13.5 M_Sun). We show that (i) ISM stripping was significantly more effective at early times than at z = 0; (ii) approximately half the gas is stripped from `galactic fountains' and half directly from the star forming disk; (iii) galaxies undergoing stripping experience ram pressure up to ~100 times the average at a given group/cluster-centric radius, because they are preferentially located in overdense ICM regions. Remarkably, stripping causes at most half the loss of the extended gas haloes surrounding our simulated satellites. These results contrast sharply with the current picture of strangulation -- removal of the ISM through star formation after stripping of the hot halo -- being the dominant mechanism quenching group and cluster satellites.

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 Bahe, Y and I. G McCarthy Star formation quenching in simulated group and cluster galaxies: when, how and why? MNRAS, Feb 2015, 447, pp 969-992 is available online at: http://dx.doi.org/10.1093/mnras/stu2293
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA; astro-ph.CO
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 17 Dec 2014 14:47
Last Modified: 07 Sep 2017 13:20
URI: http://researchonline.ljmu.ac.uk/id/eprint/260

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