ASCA Temperature Maps of Three Clusters of Galaxies: Abell 1060, AWM 7, and the Centaurus Cluster

Abstract

Abstract We present two-dimensional temperature maps of three bright clusters of galaxies (Abell 1060, AWM 7, and the Centaurus cluster), based on multi-pointing observations with the ASCA GIS. The temperatures were derived from hardness ratios by taking into account the XRT response. For the Centaurus cluster, we subtracted the central cool component using the previous ASCA and ROSAT results, and the metallicity gradients observed in AWM 7 and the Centaurus cluster were included in deriving the temperatures. The intracluster medium in Abell 1060 and AWM 7 is almost isothermal from the center to the outer regions with temperatures of 3.3 and $3.9$ keV, respectively. The Centaurus cluster exhibits remarkable hot regions within about ${30{}^{\mathrm {\prime }}}$ from the cluster center, showing a temperature increase of $+0.8$ keV from the surrounding level of 3.5 keV, and the outer cool regions with lower temperatures by $-1.3$ keV. These results imply that a strong merger has occurred in the Centaurus in the recent 2–3 Gyr, and that the central cool component has survived it. In contrast, the gas in Abell 1060 was well-mixed in an early period, which probably has prevented the development of a central cool component. In AWM 7, mixing of the gas should have occurred in a period earlier than the epoch of metal enrichment.