Based on mapping observations with ASCA , an unusual hot region with a spatial extent of 1 square degree was discovered between M87 and M49 at a center coordinate of R. A .
= 12h 27m 36s and Dec. = 9 ^ { \circ } 18 ^ { \prime } ( J2000 ) .
The X-ray emission from the region has a 2 - 10 keV flux of 1 \times 10 ^ { -11 } ergs s ^ { -1 } cm ^ { -2 } and a temperature of kT \gtrsim 4 keV , which is significantly higher than that in the surrounding medium of \sim 2 keV .
The internal thermal energy in the hot region is estimated to be VnkT \sim 10 ^ { 60 } ergs with a gas density of \sim 10 ^ { -4 } cm ^ { -3 } .
A power-law spectrum with a photon index 1.7 - 2.3 is also allowed by the data .
The hot region suggests there is an energy input due to a shock which is probably caused by the motion of the gas associated with M49 , infalling toward the M87 cluster with a velocity \gtrsim 1000 km s ^ { -1 } .