336 research outputs found
Suzaku Observations of the Supernova Remnant N23 in the Large Magellanic Cloud
X-ray emission from the supernova remnant N23 in the Large Magellanic Cloud
(LMC) is studied using the X-ray Imaging Spectrometer (XIS) onboard Suzaku.
Thanks to superior energy resolution of the XIS in the soft X-ray band, we
resolved H-like and He-like Oxygen K\alpha emission lines from N23 with
unprecedentedly high quality, and as a result, identified a new optically thin
thermal emission component with a temperature ~0.2 keV, as well as that with a
temperature of ~0.5-0.7 keV previously known. This alters the estimate of the
ionization timescale net from ~10^{10-11} cm^-3s to >~10^{12} cm^{-3}s. Under
the assumption that N23 is still in the Sedov phase, its age evaluated from the
newly discovered low temperature component is ~8000 yr, although it is possible
that N23 has already moved into the radiative phase. The abundances of the
heavy elements are found to be roughly consistent with those of the LMC
average, which indicates that the origin of the X-ray emission of N23 is
swept-up ambient material, as expected from its ionization timescale.Comment: 7 pages, 5 figures, accepted for publication in PAS
Evolution of Synchrotron X-rays in Supernova Remnants
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 how 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.Comment: 6 pages, 2 figures, ApJ, in pres
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