Open AccessThe morphology–density relation in X‐ray‐bright galaxy groups
Author(s) -
Helsdon Stephen F.,
Ponman Trevor J.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06300.x
Subject(s) - physics , astrophysics , spiral galaxy , morphology (biology) , radius , galaxy cluster , cluster (spacecraft) , elliptical galaxy , galaxy , genetics , computer security , computer science , biology , programming language
We have examined the morphological make‐up of X‐ray‐bright groups. The brighter galaxies in these groups exhibit clear morphology–density and morphology–radius relations. The group morphology–density relation is offset from the cluster relation in the sense that at a given surface density, X‐ray‐bright groups have a lower spiral fraction. After correcting for projection effects the morphology–3D density relation is still shifted towards fewer spirals for a given 3D density, in comparison with clusters. A simple model that corrects the group data for the effects of projection and for the expected higher merging rate in groups brings the morphology–density relation into good agreement with that of clusters, suggesting that the relation may be driven by two‐body interactions. The fraction of S0 galaxies in these X‐ray‐bright groups is at least as high as that observed in nearby clusters. Given the low velocity dispersion of groups, this indicates that ram pressure stripping is not the dominant mechanism for S0 formation.