N. Tsuji

EVIDENCE FOR THERMAL X-RAY LINE EMISSION FROM THE SYNCHROTRON-DOMINATED SUPERNOVA REMNANT RX J1713.7-3946

We report the first detection of thermal X-ray line emission from the supernova remnant (SNR) RX J1713.7-3946, the prototype of the small class of synchrotron dominated SNRs. A softness-ratio map generated using XMM-Newton data shows that faint interior regions are softer than bright shell regions. Using Suzaku and deep XMM-Newton observations, we have extracted X-ray spectra from the softest area, finding clear line features at 1 keV and 1.35 keV. These lines can be best explained as Ne Ly-alpha and Mg He-alpha from a thermal emission component. Since the abundance ratios of metals to Fe are much higher than solar values in the thermal component, we attribute the thermal emission to reverse-shocked SN ejecta. The measured Mg/Ne, Si/Ne, and Fe/Ne ratios of 2.0-2.6, 1.5-2.0, and <0.05 solar suggest that the progenitor star of RX J1713.7-3946 was a relatively low-mass star (<~20 M_sun), consistent with a previous inference based on the effect of stellar winds of the progenitor star on the surrounding medium. Since the mean blastwave speed of ~6000 km/s (the radius of 9.6 pc divided by the age of 1600 yr) is relatively fast compared with other core-collapse SNRs, we propose that RX J1713.7-3946 is a result of a Type Ib/c supernova whose progenitor was a member of an interacting binary. While our analysis provides strong evidence for X-ray line emission, our interpretation of its nature as thermal emission from SN ejecta requires further confirmation especially through future precision spectroscopic measurements using ASTRO-H.

Chandra and NuSTAR observations of supernova remnant RX J1713.7−3946

Galactic cosmic rays are widely thought to be accelerated at supernova remnants (SNRs). SNR RX J1713.7−3946 is the strong sources of nonthermal radiation, making it one of the most well studied particle accelerators in our Galaxy. From the Chandra measurement of the proper motions in the northwest region of RX J1713.7−3946, the blast-wave shock speed is estimated as 3900 km/s. This relatively fast shock velocity, combined with the standard analytic solutions that describe the hydrodynamical properties of SNR evolution, supports the connection with SN393, and suggests that RX J1713.7−3946 would not have exited the ejecta-dominated phase, implying that the energy of accelerated particles has not reached the maximum yet. We have recently performed hard X-ray observations of RX J1713.7−3946 with NuSTAR (3–79 keV), providing fisrt imaging observations of RX J1713.7−3946 at the hard X-ray band above 10 keV. In preliminary fashion, we present spatially-resolved spectral analysis of the northwest part of this rem...

Expansion measurements of supernova remnant RX J1713.7−3946

Supernova remnant (SNR) RX J1713.7-3946 is well known for its bright TeV gamma-ray emission with shell-like morphology. To constrain the hydrodynamical evolution, we have performed six times observations of the northwestern (NW) shell with the Chandra X-ray Observatory from 2005 to 2011, and measured the proper motion by using these data and the first epoch observation taken in 2000. The blast-wave shock speed at the NW shell is measured to be

Detecting Thermal X-Ray Emission and Proper Motions in RX J1713.7-3946

(3900\pm 300) (d/{\rm kpc})\ {\rm km}\ {\rm s}^{-1}