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arXiv · 1801.01614

The Transition from Young to Middle-aged Supernova Remnants: Thermal and Nonthermal Aspects of SNR N132D

Aya Bamba·Yutaka Ohira·Ryo Yamazaki·Makoto Sawada·Yukikatsu Terada·Katsuji Koyama·Eric D. Miller·Hiroya Yamaguchi·Satoru Katsuda·Masayoshi Nobukawa·Kumiko K. Nobukawa
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Abstract

Supernova remnants (SNRs) are the primary candidate of Galactic cosmic-ray accelerators. It is still an open issue when and how young SNRs, which typically exhibit strong synchrotron X-rays and GeV and TeV gamma-rays, undergo the state transition to middle-aged SNRs dominated by thermal X-rays and GeV gamma-rays. The SNR N132D in the Large Magellanic Cloud is an ideal target to study such a transition, exhibiting bright X-rays and gamma-rays, and with the expected age of ~2500 yrs. In this paper we present results of NuSTAR and Suzaku spectroscopy. We reveal that N132D has a nearly equilibrium plasma with a temperature of > 5 keV or a recombining plasma with a lower temperature (~1.5 keV) and a recombining timescale (net) of 8.8 (7.0--10.0)e12 cm^-3s. Together with the center filled morphology observed in the iron K line image, our results suggest that N132D is now at transition stage from a young SNR to middle-aged. We have constrained the tight upper-limit of nonthermal X-rays. Bright gamma-rays compared to faint nonthermal X-rays suggest that the gamma-rays are hadronic in origin. The spectral energy distribution from radio to gamma-rays shows a proton cut-off energy of ~30 TeV. These facts confirm that N132D is in the transition from young to middle-aged SNR. The large thermal energy of > 10^51 erg and accelerated proton energy of ~ 10^50 erg suggest the supernova explosion might have been very energetic.

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Aya Bamba, Yutaka Ohira, Ryo Yamazaki, Makoto Sawada, Yukikatsu Terada, Katsuji Koyama, Eric D. Miller, Hiroya Yamaguchi, Satoru Katsuda, Masayoshi Nobukawa, Kumiko K. Nobukawa. 2018-01-05. The Transition from Young to Middle-aged Supernova Remnants: Thermal and Nonthermal Aspects of SNR N132D. https://doi.org/10.3847/1538-4357/aaa5a0

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