X-ray Hotspots in the Northwest Shell of the Supernova Remnant RX J1713.7$-$3946. (arXiv:2006.15796v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Higurashi_R/0/1/0/all/0/1">Ryota Higurashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsuji_N/0/1/0/all/0/1">Naomi Tsuji</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uchiyama_Y/0/1/0/all/0/1">Yasunobu Uchiyama</a>

The supernova remnant (SNR) RX J1713.7$-$3946 is one of the best-studied
accelerators of cosmic rays because of its strong nonthermal X-ray and
gamma-ray radiation. We have analyzed accumulated chandra observations with a
total exposure time of $sim$266 ks in the northwest rim of RX J1713.7$-$3946.
We detect a substantially large number of point-like sources, referred to as
“hotspots”, which are likely associated with the remnant. The spectra of the
hotspots are well described by an absorbed power-law model. The spectral
properties ($10^{21} mathrm{cm^{-2}}lesssim N_H lesssim 10^{23}
mathrm{cm^{-2}}$ and $ 0.5lesssim Gamma lesssim 6$) are different from
diffuse X-ray emission in RX J1713.7$-$3946, and the harder hotspot tends to
have the larger $N_H$. We also confirm yearly and monthly variabilities of flux
for some hotspots. We propose that RX J1713.7$-$3946 is embedded in a complex
surroundings where some dense molecular clumps and cores exist inside a
wind-blown cavity, and that the hotspot traces synchrotron emission caused by
an interaction of shock waves of the SNR and dense molecular cores with a
number density of $10^{5}-10^{7}~ mathrm{cm}^{-3}$. The X-ray radiation of the
hotspot might be emitted from both primary electrons accelerated at the shocks
and secondary electrons produced by the interaction of accelerated protons with
the cores.

The supernova remnant (SNR) RX J1713.7$-$3946 is one of the best-studied
accelerators of cosmic rays because of its strong nonthermal X-ray and
gamma-ray radiation. We have analyzed accumulated chandra observations with a
total exposure time of $sim$266 ks in the northwest rim of RX J1713.7$-$3946.
We detect a substantially large number of point-like sources, referred to as
“hotspots”, which are likely associated with the remnant. The spectra of the
hotspots are well described by an absorbed power-law model. The spectral
properties ($10^{21} mathrm{cm^{-2}}lesssim N_H lesssim 10^{23}
mathrm{cm^{-2}}$ and $ 0.5lesssim Gamma lesssim 6$) are different from
diffuse X-ray emission in RX J1713.7$-$3946, and the harder hotspot tends to
have the larger $N_H$. We also confirm yearly and monthly variabilities of flux
for some hotspots. We propose that RX J1713.7$-$3946 is embedded in a complex
surroundings where some dense molecular clumps and cores exist inside a
wind-blown cavity, and that the hotspot traces synchrotron emission caused by
an interaction of shock waves of the SNR and dense molecular cores with a
number density of $10^{5}-10^{7}~ mathrm{cm}^{-3}$. The X-ray radiation of the
hotspot might be emitted from both primary electrons accelerated at the shocks
and secondary electrons produced by the interaction of accelerated protons with
the cores.

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