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تسجيل مستخدم جديدShock-Cloud Interaction in the Southwestern Rim of RX J1713.7$-$3946 Evidenced by Chandra X-ray Observations
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We report on results of Chandra X-ray observations of the southwestern part of the supernova remnant (SNR) RX J1713.7$-$3946. We measure proper motions of two X-ray bright blobs, named Blobs A and B, in regions presumably corresponding to the forward shock of the SNR. The measured velocities are $3800 pm 100~mathrm{km}~mathrm{s}^{-1}$ and $2300 pm 200~mathrm{km}~mathrm{s}^{-1}$ for Blobs A and B, respectively. Since a dense molecular clump is located close to Blob B, its slower velocity is attributed to shock deceleration as a result of a shock-cloud interaction. This result provides solid evidence that the forward shock of RX J1713.7$-$3946 is indeed colliding with dense gas discovered through radio observations reported in the literature. The locations and velocity differences of the two blobs lead to an estimate that the shock encountered with the dense gas $sim 100~mathrm{yr}$ ago. The shock velocities, together with cutoff energies of the synchrotron X-ray spectra of the blobs, indicate that particle acceleration in these regions is close to the Bohm limit. Blob B, in particular, is almost at the limit, accelerating particles at the fastest possible rate. We discuss possible influence of the shock-cloud interaction on the efficiency of particle acceleration.
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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 e
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ed in hard X-rays for the first time and significantly detected up to 50 keV. The IBIS sky image of RX J1713.7-3946, accumulated over 14 years of operations, demonstrates two extended hard X-ray sources. These sources are spatially consistent with northwest and southwest rims of RX J1713.7-3946 and are also clearly visible at energies below 10 keV with XMM-Newton. This points to a single emission mechanism operating in soft and hard X-rays. The INTEGRAL 17-120 keV spectrum of RX J1713.7-3946 is characterized by a power-law continuum with the photon index of $Gammaapprox3$, that is significantly softer than $Gammaapprox2$ determined by XMM-Newton in the 1-10 keV energy range, suggesting a progressive steepening of the spectrum with the energy.
We perform simulations of Cherenkov Telescope Array (CTA) observations of a young supernova remnant RX J1713.7-3946. This target is not only one of the brightest sources ever discovered in very high-energy gamma rays but also well observed in other w
avebands. In X-rays, the emission is dominated by synchrotron radiation, which links directly to the existence of high-energy electrons. Radio observations of CO and HI gas have revealed a highly inhomogeneous medium surrounding the SNR, such as clumpy molecular clouds. Therefore gamma rays from hadronic interactions are naturally expected. However, the spectrum in GeV energy range measured by Fermi/LAT indicates more typical of leptonic emission from accelerated electrons. Despite lots of multi-wavelength information, the competing interpretations have led to much uncertainty in the quest of unraveling the true origin of the gamma-ray emission from RX~J1713.7--3946. CTA will achieve highest performance ever in sensitivity, angular resolution, and energy resolution. We estimate CTA capability to examine the emission mechanisms of the gamma rays through simulated spatial distribution, spectra, and their time variation.
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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 positio
n 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.
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