<i>Chandra</i>Observation of the Central Galaxies in the A1060 Cluster of Galaxies

Abstract

Chandra observation of the central region of the A1060 cluster of galaxies resolved X-ray emission from two giant elliptical galaxies, NGC 3311 and NGC 3309. The emission from these galaxies consists of two components, namely the hot interstellar medium (ISM) and the low-mass X-ray binaries (LMXBs). We found the spatial extent of the ISM component was much smaller than that of stars for both galaxies, while the ratios of X-ray to optical blue-band luminosities were rather low but within the general scatter for elliptical galaxies. After subtracting the LMXB component, the ISM is shown to be in pressure balance with the intracluster medium of A1060 at the outer boundary of the ISM. These results imply that the hot gas supplied from stellar mass loss is confined by the external pressure of the intracluster medium, with the thermal conduction likely to be suppressed. The cD galaxy NGC 3311 does not exhibit the extended potential structure which is commonly seen in bright elliptical galaxies, and we discuss the possible evolution history of the very isothermal cluster A1060.