http://arxiv.org/abs/1606.07745
We have analyzed the atomic and molecular gas using the 21 cm HI and 2.6/1.3 mm CO emissions toward the TeV $\gamma$-ray supernova remnant (SNR) RCW 86 in order to identify the interstellar medium interacting with the shock waves of the SNR. We have found intensity depression in HI at a velocity range of $-46$-$-28$ km s$^{-1}$ toward the SNR, suggesting a cavity of the interstellar medium. The HI cavity corresponds with the X-ray shell consisting of thermal and non-thermal emission. The thermal X-rays are coincident with the edge of the HI distribution which indicates strong density gradient, while the non-thermal X-rays are found toward the less dense inner part of the HI cavity. The most significant non-thermal X-rays are seen toward the southwestern part of the shell where HI gas includes the dense and cold component. We also identified CO clouds which are likely interacting with the SNR shock waves in the same velocity range with HI whereas the CO clouds are distributed only in a limited part of the SNR shell. The most massive cloud is located in the southeastern part of the shell, showing detailed correspondence with the thermal X-rays. These CO clouds show an enhanced CO $J$ = 2-1/1-0 intensity ratio, suggesting heating/compression by the shock front. We interpret the present results that the shock-cloud interaction enhances non-thermal X-rays in the southwest and the thermal X-rays are emitted from the shock-heated gas of density 10-100 cm$^{-3}$. It seems likely that the progenitor of RCW 86 had low-velocity stellar winds with the white dwarf(s), because the thermal X-rays indicate the remaining medium density HI gas which was not fully swept up by the progenitor winds.
H. Sano, K. Nakamura, N. Furukawa, et. al.
Mon, 27 Jun 16
25/43
Comments: 19 pages, 15 figures, 3 tables, submitted to The Journal of High Energy Astrophysics (JHEAp)
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