Temperature Variation in the Cluster of Galaxies Abell 115 Studied withASCA

Abell 115 exhibits two distinct peaks in the surface brightness distribution.ASCA observation shows a significant temperature variation in this cluster,confirmed by a hardness ratio analysis and spectral fits. A linking regionbetween main and sub clusters shows a high temperature compared with otherregions. Two possibilities are examined as the cause of the temperaturevariation: cooling flows in the main cluster and a shock heating due to thecollision of the subcluster into the main system. Spectral fits with coolingflow models to the main-cluster data show a mass-deposition rate less than 419solar-mass/yr. Temperatures in the main cluster, the linking region, and thesubcluster are estimated by correcting for the effects of X-ray telescoperesponse as 4.9 (+0.7/-0.6), 11 (+12/-4), and 5.2 (+1.4/-1.0) keV,respectively. The high temperature in the linking region implies that Abell 115is indeed a merger system, with possible contribution from cooling flows on thetemperature structure.Comment: 23 pages, including 7 Postscript figures, accepted for publication in Ap