The Youngest Galactic Supernova Remnant: G1.9+0.3
The Youngest Galactic Supernova Remnant: G1.9+0.3
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DOI：
10.1086/589570
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发表时间：
2008-03
期刊：
影响因子：
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通讯作者：
S. Reynolds;K. Borkowski;D. Green;U. Hwang;I. Harrus;R. Petre
中科院分区：
文献类型：
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作者：
S. Reynolds;K. Borkowski;D. Green;U. Hwang;I. Harrus;R. Petre
我们对小型射电超新星遗迹（SNR） G1.9+0.3进行了50ks钱德拉观测，显示出一个完整的壳结构，具有很强的双边对称性，直径约为100″。射电的形态也是贝壳状的，但根据1985年的观测，直径只有84″左右。我们将大小差异归因于1985年和2007年钱德拉观测到的膨胀。通过比较1985年和2008年的射电图像可以证实它的膨胀。我们推断G1.9+0.3大约有100年的历史，是银河系中最年轻的超新星遗迹。基于极高的吸收柱密度（5.5 × 1022 cm−2），我们将G1.9+0.3放置在银河系中心附近，距离约8.5 kpc，平均残余半径约为2pc，所需的膨胀速度约为14000 km s−1。x射线光谱是无特征的，用指数截断同步加速器模型srcut很好地描述了它。当1 GHz的无线电通量固定为0.9 Jy时，我们发现频谱指数为0.65，滚转频率为1.4 × 1018 Hz。隐含的特征滚转电子能约为94(B/10 μ G)−1/2 TeV，是壳超新星遗迹所报道的最高电子能。它可以很容易地达到标准扩散冲击加速度，考虑到非常高的冲击速度；它可以很好地描述为年龄限制或同步加速器损失限制加速。G1.9+0.3不仅是已知最年轻的银河系遗迹，也是银河系中第四个以x射线同步加速器为主的壳超新星遗迹。
Our 50 ks Chandra observation of the small radio supernova remnant (SNR) G1.9+0.3 shows a complete shell structure with strong bilateral symmetry, about 100″ in diameter. The radio morphology is also shell-like, but only about 84″ in diameter, based on observations made in 1985. We attribute the size difference to expansion between 1985 and our Chandra observations of 2007. Expansion is confirmed in comparing radio images from 1985 and 2008. We deduce that G1.9+0.3 is of order 100 years old—the youngest supernova remnant in the Galaxy. Based on a very high absorbing column density of 5.5 × 1022 cm−2, we place G1.9+0.3 near the Galactic center, at a distance of about 8.5 kpc, where the mean remnant radius would be about 2 pc, and the required expansion speed about 14,000 km s−1. The X-ray spectrum is featureless and well described by the exponentially cut off synchrotron model srcut. With the radio flux at 1 GHz fixed at 0.9 Jy, we find a spectral index of 0.65 and a rolloff frequency of 1.4 × 1018 Hz. The implied characteristic rolloff electron energy of about 94(B/10 μ G)−1/2 TeV is the highest ever reported for a shell supernova remnant. It can easily be reached by standard diffusive shock acceleration, given the very high shock velocities; it can be well described by either age-limited or synchrotron-loss-limited acceleration. Not only is G1.9+0.3 the youngest known Galactic remnant, it is also only the fourth Galactic X-ray-synchrotron-dominated shell supernova remnant.