Interaction between the jet and the interstellar medium of M87 using   Chandra
  This study shows the existence of an additional thermal component found in the synchrotron emission from the M87 jet. Using Chandra, thermal bremsstrahlung is detected in four out of six fields. X-rays for the nucleus and HST-1 are well described with a power law model. Neutral density, plasma density, and the density of accelerated electrons for the nucleus and each part of the jet are obtained. The mass of the thermal gas is estimated to be 3.9x10^6 M. The possibility that the thermal gas is injected into the jet from the black-hole is excluded because the nucleus and the field HST-1 do not contain thermal components. It is possible that the interstellar medium is compressed by the jet and is heated by the shock. The energy density of the gas is comparable to that of the magnetic field with 1 mG. For the field D, a high density of accelerated electrons of 1.5x10^11 (2 d / tval )^3 ( 6 / delta )^3 ( 3 /Gamma )^2 m^-3 GeV^(p-1), a high upper limit of neutral density of 8 cm^-3, and a high ion density of 195 cm^-3 are obtained. A possible contribution of non-thermal bremsstrahlung from the jet, especially the field D to the observed flux with Fermi is suggested. This scenario matches with non-flux variability in the GeV energy range. 
S.Osone
astro-ph.HE