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Register a new userRXTE, ROSAT and ASCA Observations of G347.3-0.5 (RX J1713.7-3946): Probing Cosmic Ray Acceleration by a Galactic Shell-Type Supernova Remnant
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Thomas G. Pannuti
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(Abridged) We present an analysis of the X-ray spectrum of the Galactic shell-type supernova remnant (SNR) G347.3-0.5 (RX J1713.7-3946). By performing a joint spectral analysis of data from observations made of G347.3-0.5 using the ROSAT PSPC, the ASCA GIS and the RXTE PCA, we have fit the spectra of particular regions of this SNR (including the bright northwestern and southwestern rims, the northeastern rim and the interior diffuse emission) over the approximate energy range of 0.5 through 30 keV. Based on the parameters of the best fit to the spectra using the SRCUT model, we estimate the maximum energy of cosmic-ray electrons accelerated by the rims of G347.3-0.5 to be 19-25 TeV, assuming a magnetic field strength of 10 microGauss. We present a broadband (radio to gamma-ray) photon energy flux-spectrum for the northwestern rim of the SNR, using a synchrotron-inverse Compton model with a variable magnetic field strength to fit the spectrum. Our fit derived from this model yields a maximum energy of only 8.8 TeV for the accelerated cosmic-ray electrons and a magnetic field strength of 150 microGauss. However, our derived ratio of volumes for TeV emission and X-ray emission (approximately 1000) is too large to be physically acceptable. We argue that neither non-thermal bremsstrahlung nor neutral pion decay can adequately describe the TeV emission from this rim, and therefore the physical process responsible for this emission is currently uncertain. Finally, we compare the gross properties of G347.3-0.5 with other SNRs known to possess X-ray spectra dominated by non-thermal emission.
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Although the connection of the Chinese guest star of 393 AD with the Galactic supernova remnant RX J1713.7-3946 (G347.3-0.5) made by Wang et al. in 1997 is consistent with the remnants relatively young properties and the guest stars projected position within the `tail of the constellation Scorpius, there are difficulties with such an association. The brief Chinese texts concerning the 393 AD guest star make no comment about its apparent brightness stating only that it disappeared after 8 months. However, at the remnants current estimated 1 - 1.3 kpc distance and A_v ~ 3 mag, its supernova should have been a visually bright object at maximum light (-3.5 to -5.0 mag) and would have remained visible for over a year. The peak brightness ~ 0 magnitude adopted by Wang et al. and others would require the RX J1713.7-3946 supernova to have been a very subluminous supernova event similar to or fainter than CCSNe like SN 2005cs. We also note problems connecting SN 393 with a European record in which the Roman poet Claudian describes a visually brilliant star in the heavens around 393 AD that could be readily seen even in midday. Although several authors have suggested this account may be a reference to the Chinese supernova of 393, Scorpius would not be visible near midday in March when the Chinese first reported the 393 guest star. We review both the Chinese and Roman accounts and calculate probable visual brightnesses for a range of supernova subtypes and conclude that neither the Chinese nor the Roman descriptions are easily reconciled with an expected RX J1713.7-3946 supernova brightness and duration.
Supernova remnant RX J1713.7-3946 (also named as G347.3-0.5) has exhibited largest surface brightness, detailed spectral and shell-type morphology, it is one of the brightest TeV sources. The recent H.E.S.S. observation of RX J1713.7-3946 revealed textbf{a} broken power-law spectrum of GeV-TeV gamma-ray spectrum and more extended gamma-ray spatial radial profile than that in the X-ray band. Based on the diffusion shock acceleration model, we solve spherically symmetric hydrodynamic equations and transport equations of particles, and investigate multi-band non-thermal emission of RX J1713.7-3946 and radial profiles of its surface brightness for two selected zones in the leptonic scenario for the $gamma$-ray emission. We found (1) the diffusion coefficient has a weak energy-dependent, and the Kolmogorov type is favored; (2) the magnetic field strength could vary linearly or nonlinearly with radius for different surrounding environments because of possible turbulence in shock downstream region, and a compressional amplification is likely to exist at the shock front; (3) the non-thermal photons from radio to X-ray bands are dominated by synchrotron emission from relativistic electrons, if the GeV-TeV gamma-rays are produced by inverse Compton scattering from these electrons interacting with the background photons, then the X-ray and gamma-ray radial profiles can be reproduced except for the more extended $gamma$-ray emission.
We present observations of the young Supernova remnant (SNR) RX J1713.7-3946 with the Fermi Large Area Telescope (LAT). We clearly detect a source positionally coincident with the SNR. The source is extended with a best-fit extension of 0.55$^{circ} pm 0.04^{circ}$ matching the size of the non-thermal X-ray and TeV gamma-ray emission from the remnant. The positional coincidence and the matching extended emission allows us to identify the LAT source with the supernova remnant RX J1713.7-3946. The spectrum of the source can be described by a very hard power-law with a photon index of $Gamma = 1.5 pm 0.1$ that coincides in normalization with the steeper H.E.S.S.-detected gamma-ray spectrum at higher energies. The broadband gamma-ray emission is consistent with a leptonic origin as the dominant mechanism for the gamma-ray emission.
G347.3-0.5 (RX J1713.7-3946) is a member of the new class of shell-type Galactic supernova remnants (SNRs) that feature non-thermal components to their X-ray emission. We have analyzed the X-ray spectrum of this SNR over a broad energy range (0.5 to 30 keV) using archived data from observations made with two satellites, the Roentgenstaellit (ROSAT) and the Advanced Satellite for Cosmology and Astrophysics (ASCA), along with data from our own observations made with the Rossi X-ray Timing Explorer (RXTE). Using a combination of the models EQUIL and SRCUT to fit thermal and non-thermal emission, respectively, from this SNR, we find evidence for a modest thermal component to G347.3-0.5s diffuse emission with a corresponding energy of kT = 1.4 keV. We also obtain an estimate of 70 TeV for the maximum energy of the cosmic-ray electrons that have been accelerated by this SNR.
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.
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