Pre-processing and post-processing in group-cluster mergers

R. Vijayaraghavan, P. M. Ricker

Research output: Contribution to journalArticlepeer-review

Abstract

Galaxies in clusters are more likely to be of early type and to have lower star formation rates than galaxies in the field. Recent observations and simulations suggest that cluster galaxies may be 'pre-processed' by group or filament environments and that galaxies that fall into a cluster as part of a larger group can stay coherent within the cluster for up to one orbital period ('post-processing').We investigate these ideas by means of a cosmological N-body simulation and idealized N-body plus hydrodynamics simulations of a group-cluster merger. We find that group environments can contribute significantly to galaxy pre-processing by means of enhanced galaxy-galaxy merger rates, removal of galaxies' hot halo gas by ram pressure stripping and tidal truncation of their galaxies. Tidal distortion of the group during infall does not contribute to pre-processing. Post-processing is also shown to be effective: galaxy-galaxy collisions are enhanced during a group's pericentric passage within a cluster, the merger shock enhances the ram pressure on group and cluster galaxies and an increase in local density during the merger leads to greater galactic tidal truncation.

Original languageEnglish (US)
Pages (from-to)2713-2735
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Volume435
Issue number3
DOIs
StatePublished - Nov 2013

Keywords

  • Galaxies: Clusters: General
  • Galaxies: Clusters: Intracluster medium
  • Galaxies: Evolution
  • Galaxies: Groups: General
  • Methods: Numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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