Presentation #116.117 in the session Stellar/Compact Objects.
Quantifying whether Supernova Remnants (SNR) are the primary acceleration source of Galactic cosmic rays is a significant problem. SNR with a non-thermal dominated spectrum (ND-SNR) accelerates particles with high efficiency. Therefore, quantitative evaluation of the occurrence rate of ND-SNR is essential to quantitatively evaluate SNRs' contribution to Galactic cosmic rays. However, we still do not know the exact occurrence rate. To solve this problem, we focused on the fact that the occurrence rate can be estimated by comparing the mass of the progenitor star to the initial mass function.
We report the discovery of a CSM knot inside the ND-SNR RX J1713.7-3946 and the mass estimation of the progenitor as an intermediate step. This knot was considered a Wolf-Rayet star (WR 85), but our analysis indicated no relation to it. Our XMM-Newton/RGS observation reveals line emissions from N, O, Ne, Mg, Si, and Fe. We fitted the spectrum with an absorbed thermal emission model and found that the N abundance was enriched N/H=3.5±0.8 (N/H)solar, and others are about the solar abundance. These results conclude that this knot is CSM ejected when the progenitor star evolved into an RSG. From the abundance ratio of N to O and comparing it to those in outer layers of RSG stars expected from stellar evolution simulations, we estimate the initial mass of the progenitor star to be 15-20 Msun. The fact that the progenitor star is not massive (<30 Msun) suggests that ND-SNR is relatively universal.
Next, we discuss the thermal X-ray from ND-SNR RX J0852.0-4622. From our imaging analysis of Super COSMOS, we discovered that the Hα radiation correlates with synchrotron radiation and CO molecular clouds of the SNR. Moreover, the line intensity ratio of the UV band in this region differs from that of the Vela SNR, which overlaps in the direction of the line of sight (Kim et al., 2012). These results suggest the existence of thermal plasma of the SNR. This assertion is also supported by the fact that Suzaku/XIS shows an excess component in the band below 1 keV, which the synchrotron radiation of the SNR cannot explain. We report the results of the mass estimation of the progenitor star when this excess component is observed with XRISM/Resolve.