The XMM Large-Scale Structure survey: an initial sample of galaxy groups and clusters to a redshift z < 0.6*
Altieri, B.; Valtchanov, I.; Pierre, M.; Dos Santos, S.; Jones, L.; Andreon, S.; Bremer, M.; Duc, P. -A.; Gosset, E.; Surdej, J.; Galaz, G.; Birkinshaw, M.; Pacaud, F.; Willis, J. P.; Quintana, H.; Ponman, T.; Read, A.
Canada, France, United Kingdom, Italy, Spain, Chile, Belgium
Abstract
We present X-ray and optical spectroscopic observations of 12 galaxy groups and clusters identified within the X-ray Multi-Mirror (XMM) Large-Scale Structure (LSS) survey. Groups and clusters are selected as extended X-ray sources from a 3.5 deg2XMM image mosaic above a flux limit 8 × 10-15 erg s-1 cm-2 in the [0.5-2] keV energy band. Deep BVRI images and multi-object spectroscopy confirm each source as a galaxy concentration located within the redshift interval 0.29 < z < 0.56. We combine line-of-sight velocity dispersions with the X-ray properties of each structure computed from a two-dimensional surface brightness model and a single temperature fit to the XMM spectral data. The resulting distribution of X-ray luminosity, temperature and velocity dispersion indicate that the XMM-LSS survey is detecting low-mass clusters and galaxy groups to redshifts z < 0.6. Confirmed systems display little or no evidence for X-ray luminosity evolution at a given X-ray temperature compared to lower-redshift X-ray group and cluster samples. A more complete understanding of these trends will be possible with the compilation of a statistically complete sample of galaxy groups and clusters anticipated within the continuing XMM-LSS survey.