Detection of an X-Ray Hot Region in the Virgo Cluster of Galaxies with ASCA

Based on mapping observations with ASCA, an unusual hot region with a spatial extent of 1 deg2 was discovered between M87 and M49 at a center coordinate of R.A. = 12h27m36s and decl. = 9°18′ (J2000). The X-ray emission from the region has a 2-10 keV flux of 1 × 10-11 ergs s-1 cm-2 and a temperature of kT ≳ 4 keV, which is significantly higher than that in the surrounding medium of ~2 keV. The internal thermal energy in the hot region is estimated to be VnkT ~ 1060 ergs with a gas density of ~10-4 cm-3. A power-law spectrum with a photon index of 1.7-2.3 is also allowed by the data. The hot region suggests there is an energy input due to a shock that is probably caused by the motion of the gas associated with M49, infalling toward the M87 cluster with a velocity ≳1000 km s-1.