Galaxy groups and low mass clusters at z<0.6: A perspective from the XMM   Large Scale Structure survey
  Galaxy groups and low-mass clusters provide important laboratories in which to study X-ray gas physics and the interplay between galaxy evolution and environmental effects. The X-ray Multi-Mirror (XMM) Large Scale Structure (LSS) survey has currently imaged 5 deg2 to a nominal extended source flux limit of order 10e-14 ergs/s/cm2 and is dominated numerically by low-mass groups and clusters at redshifts 0.2 < z < 0.6. We discuss the generation of the XMM-LSS cluster sample, initial results on the physics of groups and low-mass clusters and the prospects for detailed follow-up studies of these systems. 
J.P. Willis, F. Pacaud, M. Pierre