New Tests of the Cluster Entropy Floor Hypothesis
  Recent efforts to account for the observed X-ray luminosity - temperature relation of galaxy clusters has led to suggestions that the ICM has an apparent ``entropy floor'' at or above the level of 300 keV cm^2. Here, we propose new tests based on the thermal Sunyaev-Zeldovich effect and on the cluster gas mass - temperature trend (from X-ray data) to probe the level of excess entropy in the ICM. We show that these new tests lend further support to the case for a high entropy floor in massive clusters. 
Ian G. McCarthy (1), Arif Babul (1), Michael L. Balogh (2), and   Gilbert P. Holder (3) ((1) University of Victoria, (2) Uni...