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arXiv · 1103.0348

X-Ray Spectrum of a Peculiar Supernova Remnant G359.1-0.5

Takao Ohnishi·Katsuji Koyama·Takeshi Go Tsuru·Kuniaki Masai·Hiroya Yamaguchi·Midori Ozawa
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Abstract

We present the Suzaku results of a supernova remnant (SNR), G359.1-0.5 in the direction of the Galactic center region. From the SNR, we find prominent K-shell lines of highly ionized Si and S ions, together with unusual structures at 2.5-3.0 and 3.1-3.6 keV. No canonical SNR plasma model, in either ionization equilibrium or under-ionization, can explain the structures. The energies and shapes of the structures are similar to those of the radiative transitions of free electrons to the K-shell of He-like Si and S ions (radiative recombination continuum: RRC). The presence of the strong RRC structures indicates that the plasma is in over-ionization. In fact, the observed spectrum is well fitted with an over-ionized plasma model. The best-fit electron temperature of 0.29 keV is far smaller than the ionization temperature of 0.77 keV, which means that G359.1-0.5 is in extreme condition of over-ionization. We report some cautions on the physical parameters, and comment possible origins for the over-ionized plasma.

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Takao Ohnishi, Katsuji Koyama, Takeshi Go Tsuru, Kuniaki Masai, Hiroya Yamaguchi, Midori Ozawa. 2011-03-02. X-Ray Spectrum of a Peculiar Supernova Remnant G359.1-0.5. https://doi.org/10.1093/pasj%2F63.3.527

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