Temperature Map of the Virgo Cluster of Galaxies Observed withASCA

The temperature distribution of the intracluster medium (ICM) in the Virgocluster of galaxies has been derived from extensive mapping observations withASCA covering an area of 19 deg^2. In the spectral analysis, the inner regionwithin a radius of ~60' from M87 is characterized by an ICM temperature of kT\~2.5 keV with little variation. On the other hand, the outer regions indicatesignificant variation of the temperature with an amplitude of about 1 keV. Thetemperature map was produced from the hardness ratio (H.R.) values with aresolution of about 5'. Besides the previously reported hot region with kT > 4keV between M87 and M49, several hot regions with kT = 3-4 keV are detected inthe cluster outskirts. The auto-correlation function for the H.R. variationshows that the temperature variation is correlated within a size of about 300kpc, suggesting that gas blobs falling in the Virgo cluster have a typical sizeof groups of galaxies. A correlation with the velocity dispersion of membergalaxies shows that only the north-west region indicates an unusually largebeta_spec value of 2-4. The upper limit for extended non-thermal emission inthe Virgo cluster is obtained to be L_X ~9 x 10^41 ergs/s in the 2 - 10 keVband. We discuss that these features consistently indicate that the Virgocluster is in a relatively early stage of the cluster evolution.Comment: 37 pages, including 12 Postscript figures, accepted for publication in Ap