We present a combined X-ray and optical analysis of the cold front cluster Abell 1201 using archival Chandra data and multi-object spectroscopy taken with the 3.9m Anglo Australian and 6.5m Multiple Mirror Telescopes .
This paper represents the first in a series presenting a study of a sample of cold front clusters selected from the Chandra archives with the aim of relating cold fronts to merger activity , understanding the dynamics of mergers and their effect on the cluster constituents .
The Chandra X-ray imagery of Abell 1201 reveals two conspicuous surface brightness discontinuities , which are shown to be cold fronts , and a remnant core structure .
Temperature maps reveal a complex multi-phase temperature structure with regions of hot gas interspersed with fingers of cold gas .
Our optical analysis is based on a sample of 321 confirmed members , whose mean redshift is z = 0.1673 \pm 0.0002 and velocity dispersion is 778 \pm 36 { km s ^ { -1 } } .
We search for dynamical substructure and find clear evidence for multiple localized velocity substructures coincident with over-densities in the galaxy surface density .
Most notably , we find structure coincident with the remnant X-ray core .
Despite the clear evidence for dynamical activity , we find the peculiar velocity distribution does not deviate significantly from Gaussian .
We apply two-body dynamical analyses in order to assess which of the substructures are bound , and thus dynamically important in terms of the cluster merger history .
We propose that the cold fronts in Abell 1201 are a consequence of its merger with a smaller subunit , which has induced gas motions that gave rise to ‘ sloshing ’ cold fronts .
Abell 1201 illustrates the value of combining multi-wavelength data and multiple substructure detection techniques when attempting to ascertain the dynamical state of a cluster .