2000ApJ...531L..95K

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.=12^h27^m36^s and decl.=9°18' (J2000). The X-ray emission from the region has a 2-10 keV flux of 1x10^–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.