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arXiv 1406.2287astro-ph.HEastro-ph.SR
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最年轻的银河系超新星遗迹G1 .9+0.3的非均匀膨胀

Nonuniform Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3

K. J. Borkowski, S. P. Reynolds, D. A. Green, U. Hwang, R. Petre, K. Krishnamurthy, R. Willett

摘要:

我们报告了2007年,2009年和2011年使用钱德拉观测的最年轻的银河系超新星遗迹G1.9+0.3的X射线膨胀测量结果。测量的速率强烈偏离均匀膨胀,沿X射线明亮的SE-NW轴径向减少约60%,从每年0.84% +/- 0.06%到每年0.52% +/- 0.03%。这相当于120-190年的未减速年龄,证实了G1.9+0.3的年轻年龄,并意味着爆炸波的显著减速。同步加速器主导的X射线发射以每年1.9% +/- 0.4%的速度变亮。我们确定明亮的外部和内部边缘的冲击波和反向冲击波,分别。在喷出物或周围介质中,都需要有急剧的密度梯度,才能产生反向冲击波或爆炸波的突然减速,这是由膨胀年龄中的大范围传播所暗示的。爆炸波可能是最近遇到的周围介质中的一个适度的密度不连续性,如发现在风终止冲击,需要在祖强质量损失减速。或者,反向冲击波可能遇到了一个数量级的密度不连续的喷出物,如发现在脉动延迟爆炸Ia型模型。我们证明,在这些模型中,对于年龄类似于G1.9+0.3的遗迹,冲击波比反向冲击波减速得多。可能与Ia型光谱中的高速特征有关的致密壳层也可能产生类似的效应。考虑到G1.9+0.3的不对称性,将需要更逼真的3D Ia型模型。

英文摘要:

We report measurements of X-ray expansion of the youngest Galactic supernova remnant, G1.9+0.3, using Chandra observations in 2007, 2009, and 2011. The measured rates strongly deviate from uniform expansion, decreasing radially by about 60% along the X-ray bright SE-NW axis from 0.84% +/- 0.06% per yr to 0.52% +/- 0.03% per yr. This corresponds to undecelerated ages of 120-190 yr, confirming the young age of G1.9+0.3, and implying a significant deceleration of the blast wave. The synchrotron-dominated X-ray emission brightens at a rate of 1.9% +/- 0.4% per yr. We identify bright outer and inner rims with the blast wave and reverse shock, respectively. Sharp density gradients in either ejecta or ambient medium are required to produce the sudden deceleration of the reverse shock or the blast wave implied by the large spread in expansion ages. The blast wave could have been decelerated recently by an encounter with a modest density discontinuity in the ambient medium, such as found at a wind termination shock, requiring strong mass loss in the progenitor. Alternatively, the reverse shock might have encountered an order-of-magnitude density discontinuity within the ejecta, such as found in pulsating delayed-detonation Type Ia models. We demonstrate that the blast wave is much more decelerated than the reverse shock in these models for remnants at ages similar to G1.9+0.3. Similar effects may also be produced by dense shells possibly associated with high-velocity features in Type Ia spectra. Accounting for the asymmetry of G1.9+0.3 will require more realistic 3D Type Ia models.

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