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Register a new userSuzaku Observation of 30Dor C: A Supernova Remnant with the Largest Non-Thermal Shell
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This paper reports on the Suzaku results of thermal and non-thermal features of 30 Dor C, a supernova remnant (SNR) in a superbubble of the Large Magellanic Cloud (LMC). The west rim exhibits a non-thermal X-ray spectrum with no thermal component. A single power-law model is rejected but a power-law model with spectral cutoff is accepted. The cutoff frequency of $(3-7)times 10^{17}$ Hz is the highest among the shell type SNRs like SN 1006 ($sim 6times 10^{16}$ Hz), and hence 30 Dor C would be the site of the highest energy accelerator of the SNR shock. The southeast (SE) and northeast (NE) rims have both the thermal and non-thermal components. The thin-thermal plasmas in the both rims are in collisional ionization equilibrium state. The electron temperature of the plasma in the SE rim ($kT_e sim 0.7$ keV) is found to be higher than the previously reported value. The power-law index from SE is nearly the same as, while that from the NE is larger than that of the West rim. The SNR age would be in the range of $(4-20)times 10^3$ yr. Thus, 30 Dor C is likely to be the oldest shell-like SNR with non-thermal emission.
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A detailed analysis of the nonthermal X-ray emission from the North-Western and Southern parts of the supernova remnant (SNR) HESS J1731$ - $347 with {it Suzaku} is presented. The shell portions covered by the observations emit hard and line-less X-rays. The spectrum can be reproduced by a simple absorbed power-law model with a photon index $Gamma$ of 1.8-2.7 and an absorption column density $N_{rm H}$ of (1.0-2.1)$times 10^{22}$ cm$^{-2}$. These quantities change significantly from region to region; the North-Western part of the SNR has the hardest and most absorbed spectrum. The Western part of the X-ray shell has a smaller curvature than North-Western and Southern shell segments. A comparison of the X-ray morphology to the Very High Energy (VHE) gamma-ray and radio images was performed. The efficiency of electron acceleration and emission mechanism in each portion of the shell are discussed. Thermal X-ray emission from the SNR was searched for but could not be detected at a significant level.
This paper presents archival ROSAT PSPC observations of the G65.2+5.7 supernova remnant (also known as G65.3+5.7). Little material obscures this remnant and so it was well observed, even at the softest end of ROSATs bandpass (~0.11 to 0.28 keV). These soft X-ray images reveal the remnants centrally-filled morphology which, in combination with existing radio frequency observations, places G65.2+5.7 in the thermal composite (mixed morphology) class of supernova remnants. Not only might G65.2+5.7 be the oldest known thermal composite supernova remnant, but owing to its optically revealed cool, dense shell, this remnant supports the proposal that thermal composite supernova remnants lack X-ray bright shells because they have evolved beyond the adiabatic phase. These observations also reveal a slightly extended point source centered on RA = 19h 36m 46s, dec = 30deg 40 07 and extending 6.5 arcmin in radius in the band 67 map. The source of this emission has yet to be discovered, as there is no known pulsar at this location.
We analyze the Suzaku XIS data of the central region of supernova remnant G332.5-5.6. The X-ray data are well described by a single non-equilibrium ionization thermal model, {tt vnei}, with an absorbing hydrogen column density of 1.4$^{+0.4}_{-0.1}$ $times$ 10$^{21}$ cm$^{-2}$. The plasma is characterized by an electron temperature of 0.49$^{+0.08}_{-0.06}$ keV with subsolar abundances for O (0.58$^{+0.06}_{-0.05}$ solar value) and Fe (0.72$^{+0.06}_{-0.05}$ solar value) and slightly overabundance for Mg (1.23$^{+0.14}_{-0.14}$ solar value). It seems that the central X-ray emission originates from projection effect or evaporation of residual clouds inside G332.5-5.6. We estimate a distance of 3.0 $pm$ 0.8 kpc for G332.5-5.6 based on the extinction-distance relation. G332.5-5.6 has an age of 7 - 9 kyr.
We present results from X-ray analysis of a Galactic middle-aged supernova remnant (SNR) G156.2+5.7 which is bright and largely extended in X-ray wavelengths, showing a clear circular shape (radius about 50). Using the Suzaku satellite, we observed this SNR in three pointings; partially covering the northwestern rim, the eastern rim, and the central portion of this SNR. In the northwestern rim and the central portion, we confirm that the X-ray spectra consist of soft and hard-tail emission, while in the eastern rim we find no significant hard-tail emission. The soft emission is well fitted by non-equilibrium ionization (NEI) model. In the central portion, a two-component (the interstellar medium and the metal-rich ejecta) NEI model fits the soft emission better than a one-component NEI model from a statistical point of view. The relative abundances in the ejecta component suggest that G156.2+5.7 is a remnant from a core-collapse SN explosion whose progenitor mass is less than 15 M_solar. The origin of the hard-tail emission is highly likely non-thermal synchrotron emission from relativistic electrons. In the northwestern rim, the relativistic electrons seem to be accelerated by a forward shock with a slow velocity of about 500 km/sec.
Diffusive shock acceleration by the shockwaves in supernova remnants (SNRs) is widely accepted as the dominant source for Galactic cosmic rays. However, it is unknown what determines the maximum energy of accelerated particles. The surrounding environment could be one of the key parameters. The SNR RCW 86 shows both thermal and non-thermal X-ray emission with different spatial morphologies. These emission originate from the shock-heated plasma and accelerated electrons respectively, and their intensities reflect their density distributions. Thus, the remnant provides a suitable laboratory to test possible association between the acceleration efficiency and the environment. In this paper, we present results of spatially resolved spectroscopy of the entire remnant with Suzaku. The spacially-resolved spectra are well reproduced with a combination of a power-law for synchrotron emission and a two-component optically thin thermal plasma, corresponding to the shocked interstellar medium (ISM) with kT of 0.3-0.6 keV and Fe-dominated ejecta. It is discovered that the photon index of the nonthermal component becomes smaller with decreasing the emission measure of the shocked ISM, where the shock speed has remained high. This result implies that the maximum energy of accelerated electrons in RCW 86 is higher in the low-density and higher shock speed regions.
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