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Register a new userStudy of Nonthermal Emission from SNR RX J1713.7-3946 with Suzaku
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We present results obtained from a series of observations of the supernova remnant RX J1713.7-3946 by the Suzaku satellite. The observations cover about two-thirds of the remnant surface. We successfully detected hard X-rays up to ~ 40 keV from each pointing. The hard X-ray spectra are described by power-law functions with photon indices of ~ 3.0, which are larger than those in the energy region below 10 keV. Connection of the spatially-integrated XIS and HXD spectra clearly reveals a spectral cutoff in the 0.4--40 keV X-ray spectrum. This cutoff is interpreted to correspond to the maximum acceleration energy of electrons emitting synchrotron radiation. The wide-band coverage of Suzaku for the first time allows us to derive the parent electron spectrum in the cutoff region, which shows good agreement with theoretical predictions. The inferred cutoff energy in the spatially-integrated X-ray spectrum indicates that particle acceleration in the remnant is so efficient that it is almost at the theoretical limit, the so-called Bohm limit. Based on the Suzaku data, we present results of multi-wavelength studies from spectral and morphological points of view. The spectral energy distribution favors the hadronic scenario rather than the leptonic scenario. For the morphology studies, we compare the surface brightness maps from the Suzaku XIS and the H.E.S.S. telescope. We confirm the strong correlation between X-ray and TeV gamma-ray emission. In addition to the correlation, we found that in the bright western rim regions the X-ray emission is brighter than expected from the general X-ray to gamma-ray correlation.
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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.
We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX~J1713.7$-$3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very-high-energy (VHE) gamma rays. Special attention is paid to explore possible spatial (anti-)correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H{sc i} emission. We present a series of simulated images of RX J1713.7$-$3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the non-thermal X-ray emission observed by {it XMM-Newton}, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H{sc i} observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic vs leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.
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.
The origin of the radiation observed in the region of the supernova remnant RX J1713.7-3946, one of the brightest TeV emitters, has been debated since its discovery. The existence of atomic and molecular clouds in this object supports the idea that part of the GeV gamma rays in this region originate from proton-proton collisions. However, the observed column density of protons derived from gas observations cannot explain the whole emission. Yet there could be a fraction of protons contained in fainter structures that have note been detected so far. Here we search for faint objects in the line of sight of RX J1713.7-3946 using the principle of light extinction and the ESA/Gaia DR2 astrometric and photometric data. We reveal and locate with precision a number of dust clouds and note that only one appears to be in the vicinity of RX J1713.7-3946. We estimate the embedded mass to $M_{dust} = (7.0 pm 0.6) times 10^3 , M_{odot}$ which might be big enough to contain the missing protons. Finally, using the fact that the supernova remnant is expected to be located in a dusty environment and that there appears to be only one such structure in the vicinity of RX J1713.7-3946, we set a very precise constrain to the supernova remnant distance, at ($1.12 pm 0.01$) kpc.
Evidence is accumulating suggesting that collisionless shocks in supernova remnants (SNRs) can amplify the interstellar magnetic field to hundreds of microgauss or even milli-gauss levels, as recently claimed for SNR RX J1713.7-3946. If these fields exist, they are almost certainly created by magnetic field amplification (MFA) associated with the efficient production of cosmic rays by diffusive shock acceleration (DSA) and their existence strengthens the case for SNRs being the primary source of galactic cosmic ray ions to the `knee and beyond. However, the high magnetic field values in SNRs are obtained exclusively from the interpretation of observations of radiation from relativistic electrons and if MFA via nonlinear DSA produces these fields the magnetic field that determines the maximum ion energy will be substantially less than the field that determines the maximum electron energy. We use results of a steady-state Monte Carlo simulation to show how nonlinear effects from efficient cosmic ray production and MFA reduce the maximum energy of protons relative to what would be expected from test-particle acceleration.
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