DISCOVERY OF STRONG RADIATIVE RECOMBINATION CONTINUA FROM THE SUPERNOVA REMNANT IC 443 WITH SUZAKU
DISCOVERY OF STRONG RADIATIVE RECOMBINATION CONTINUA FROM THE SUPERNOVA REMNANT IC 443 WITH SUZAKU
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DOI：
10.1088/0004-637x/705/1/l6
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发表时间：
2009-09
期刊：
影响因子：
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通讯作者：
H. Yamaguchi;M. Ozawa;K. Koyama;K. Masai;J. Hiraga;M. Ozaki;D. Yonetoku
中科院分区：
文献类型：
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作者：
H. Yamaguchi;M. Ozawa;K. Koyama;K. Masai;J. Hiraga;M. Ozaki;D. Yonetoku
我们提出了银河系中年超新星遗迹（SNR） IC 443的Suzaku光谱研究。1.75-6.0 keV波段的x射线光谱由一个电子温度为~ 0.6 keV的光学薄热等离子体和几个附加的莱曼谱线来描述。我们首次在2.7 keV和3.5 keV附近检测到类h Si和S的强辐射复合连续体（RRC）。由RRC与He-like Kα谱线的强度比测定的Si和S的电离温度分别为~ 1.0 keV和~ 1.2 keV。因此，我们找到了一个极端过度电离（重组）等离子体的确凿证据。作为过电离的起源，我们的新结果不赞成以前工作中提出的热传导情景。我们认为，高电离气体是在信噪比演化的初始阶段在大质量前体周围的密集区域产生的，而低电子温度是由于绝热膨胀的快速冷却造成的。
We present the Suzaku spectroscopic study of the Galactic middle-aged supernova remnant (SNR) IC 443. The X-ray spectrum in the 1.75–6.0 keV band is described by an optically thin thermal plasma with the electron temperature of ∼0.6 keV and several additional Lyman lines. We robustly detect, for the first time, strong radiative recombination continua (RRC) of H-like Si and S around at 2.7 and 3.5 keV. The ionization temperatures of Si and S determined from the intensity ratios of the RRC to He-like Kα lines are ∼1.0 keV and ∼1.2 keV, respectively. We thus find firm evidence for an extremely overionized (recombining) plasma. As the origin of the overionization, a thermal conduction scenario argued in previous work is not favored in our new results. We propose that the highly ionized gas was made at the initial phase of the SNR evolution in dense regions around a massive progenitor, and the low electron temperature is due to a rapid cooling by an adiabatic expansion.