Discovery of recombining plasma inside the extended gamma-ray supernova remnant HB9. (arXiv:1907.01017v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Sezer_A/0/1/0/all/0/1">Aytap Sezer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ergin_T/0/1/0/all/0/1">Tulun Ergin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yamazaki_R/0/1/0/all/0/1">Ryo Yamazaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sano_H/0/1/0/all/0/1">Hidetoshi Sano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fukui_Y/0/1/0/all/0/1">Yasuo Fukui</a>
We present the results from the Suzaku X-ray Imaging Spectrometer observation
of the mixed-morphology supernova remnant HB9 (G160.9+2.6). In the west region
of HB9, we discovered recombining plasma (RP) and the spectra are well
described by a model having collisional ionization equilibrium (CIE) and RP
components, whereas the spectra in the east region are best reproduced by the
CIE and non-equilibrium ionization model. We discuss possible scenarios to
explain the origin of the RP in the west region based on the observational
properties and concluded that the rarefaction scenario is a possible
explanation for the existence of RP. Additionally, the gamma-ray emission,
morphology and spectrum in the energy range of 200 MeV to 300 GeV are
investigated using $sim$10 years of data from the Fermi Large Area Telescope
(LAT). We detected three gamma-ray point sources at a significance levels of
$sim$15$sigma$, $sim$10$sigma$ and $sim$6$sigma$, two of which are
situated within the radio shell of HB9. In order to understand the connection
between HB9 and its ambient density, we investigated the archival HI and CO
data. We detected an expanding shell structure in the velocity range of $-10.5$
and $+1.8$ km s$^{-1}$ that is coinciding with one of the gamma-ray point
sources located at the southern rim of the HB9 radio shell. On the other hand,
the RP emission is detected close to the center of the SNR which has a
relatively lower ambient density.
We present the results from the Suzaku X-ray Imaging Spectrometer observation
of the mixed-morphology supernova remnant HB9 (G160.9+2.6). In the west region
of HB9, we discovered recombining plasma (RP) and the spectra are well
described by a model having collisional ionization equilibrium (CIE) and RP
components, whereas the spectra in the east region are best reproduced by the
CIE and non-equilibrium ionization model. We discuss possible scenarios to
explain the origin of the RP in the west region based on the observational
properties and concluded that the rarefaction scenario is a possible
explanation for the existence of RP. Additionally, the gamma-ray emission,
morphology and spectrum in the energy range of 200 MeV to 300 GeV are
investigated using $sim$10 years of data from the Fermi Large Area Telescope
(LAT). We detected three gamma-ray point sources at a significance levels of
$sim$15$sigma$, $sim$10$sigma$ and $sim$6$sigma$, two of which are
situated within the radio shell of HB9. In order to understand the connection
between HB9 and its ambient density, we investigated the archival HI and CO
data. We detected an expanding shell structure in the velocity range of $-10.5$
and $+1.8$ km s$^{-1}$ that is coinciding with one of the gamma-ray point
sources located at the southern rim of the HB9 radio shell. On the other hand,
the RP emission is detected close to the center of the SNR which has a
relatively lower ambient density.
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