TEMPERATURE VARIATION IN THE CLUSTER OF GALAXIES ABELL 115 STUDIED WITH ASCA

摘要

Abell 115 exhibits two distinct peaks in the surface brightness distribution. Observation with ASCA shows a significant temperature variation in this cluster, confirmed by a hardness ratio analysis and spectral fits. A linking region between the main cluster and subcluster shows a high temperature com- pared with other regions. Two possibilities are examined as the cause of the temperature variation: cooling flows in the main cluster and a shock heating due to the collision of the subcluster into the main system. Spectral fits with cooling flow models to the main-cluster data show a mass-deposition rate less than 419 Mo yr-1. Temperatures in the main cluster, the linking region, and the subcluster are esti- mated by correcting for the effects of X-ray telescope response as 4.9~+0.7-0.6, ll~+12-1.0 and 5.2+1.4-1.0 keV, respectively. The high temperature in the linking region implies that Abell 115 is indeed a merger system, with possible contribution from cooling flows on the temperature structure.