A systematic study of the synchrotron X-ray emission from supernova remnants (SNRs) has been conducted. We selected a total of 12 SNRs whose synchrotron X-ray spectral parameters are available in the literature with reasonable accuracy, and studied h
ow their luminosities change as a function of radius. It is found that the synchrotron X-ray luminosity tends to drop especially when the SNRs become larger than ~5 pc, despite large scatter. This may be explained by the change of spectral shape caused by the decrease of the synchrotron roll-off energy. A simple evolutionary model of the X-ray luminosity is proposed and is found to reproduce the observed data approximately, with reasonable model parameters. According to the model, the total energy of accelerated electrons is estimated to be 10^(47-48) ergs, which is well below the supernova explosion energy. The maximum energies of accelerated electrons and protons are also discussed.
We report on Suzaku and Chandra observations of the young supernova remnant CTB37B, from which TeV gamma-rays were detected by the H.E.S.S. Cherenkov telescope. The 80 ks Suzaku observation provided us with a clear image of diffuse emission and high-
quality spectra. The spectra revealed that the diffuse emission is comprised of thermal and non-thermal components. The thermal component can be represented by an NEI model with a temperature, a pre-shock electron density and an age of 0.9(0.7-1.1) keV, 0.4(0.3-0.5) cm^{-3} and 650(350-3150) yr, respectively. This suggests that the explosion of CTB37B occurred in a low-density space. A non-thermal power-law component was found from the southern region of CTB37B. Its photon index of ~1.5 and a high roll-off energy (>15 keV) indicate efficient cosmic-ray acceleration. A comparison of this X-ray spectrum with the TeV gamma-ray spectrum leads us to conclude that the TeV gamma-ray emission seems to be powered by either multi-zone Inverse Compton scattering or the decay of neutral pions. The point source resolved by Chandra near the shell is probably associated with CTB37B, because of the common hydrogen column density with the diffuse thermal emission. Spectral and temporal characteristics suggest that this source is a new anomalous X-ray pulsar.
We present {it Chandra} HETG observations of SS Cygni in quiescence and outburst. The spectra are characterized by He-like and H-like Ka emission lines from O to Fe, as well as L-shell emission lines from Fe. In quiescence, the spectra are dominated
by the H-like Ka lines, whereas in outburst the He-like lines are as intense as the H-like lines. In outburst, the H-like Ka lines from O to Si are broad, with widths of 4--14 eV in Gaussian $sigma$ (1800--2300$ {rm km s^{-1}}$). The large line widths, together with line profiles, indicate that the line-emitting plasma is associated with the Keplerian disk and still retains the azimuthal bulk motion. In quiescence, the emission lines are narrower, with a Gaussian $sigma$ of 1--3 eV (420--620$ {rm km s^{-1}}$). A slightly larger velocity for lighter elements suggests that the lines in quiescence are emitted from an ionizing plasma at the entrance of the boundary layer, where the bulk motion of the optically thick accretion disk is converted into heat due to friction. Using the line intensity ratio of He-like and H-like Ka lines for each element, we have also investigated the temperature distribution in the boundary layer both in quiescence and outburst. The distribution of SS Cyg is found to be consistent with other dwarf novae investigated systematically with {it ASCA} data.
