Abell 315 spectroscopic dataset

We estimated the cluster mass from the projected phase-space distribution of cluster members using the MAMPOSSt method. In doing this estimate we took into account the presence of substructures that we were able to identify. We identify several cluster substructures.

The main two have an overlapping spatial distribution, suggesting a (past or ongoing) collision along the line-of-sight. After accounting for the presence of substructures, the mass estimate of Abell 315 from 14 kinematics is reduced by a factor 4, down to M_200_=0.8_-0.4_^+0.6^10+14M_{sun}_. We also find evidence that the cluster mass concentration is unusually low, c_200_=r_200_/r_-2_<1.

Using our new estimate of c200 we revise the weak lensing mass estimate down to M_200_=1.8_-0.9_^+1.7^10+14M_{sun}_. Our new mass estimates are in agreement with that derived from the cluster X-ray luminosity via a scaling relation, M_200_=0.9+/-0.2*10^14^M_{sun}_. Abell 315 no longer belongs to the class of X-ray underluminous clusters.

Its mass estimate was inflated by the presence of an undetected subcluster in collision with the main cluster. Whether the presence of undetected line-of-sight structures can be a general explanation for all X-ray underluminous clusters remains to be explored using a statistically significant sample.