Electron Heating and Cosmic Rays at a Supernova Shock from Chandra X-Ray Observations of 1E 0102.2–7219
Electron Heating and Cosmic Rays at a Supernova Shock from Chandra X-Ray Observations of 1E 0102.2–7219
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DOI：
10.1086/312945
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发表时间：
2000-07
期刊：
影响因子：
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通讯作者：
J. Hughes;C. Rakowski;A. Decourchelle
中科院分区：
文献类型：
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作者：
J. Hughes;C. Rakowski;A. Decourchelle
在这封信中，我们使用钱德拉X射线天文台前所未有的空间分辨率，首次对年轻超新星遗迹的冲击后电子温度和自行运动进行测量，特别是为了解决电子，离子和宇宙射线之间的能量分配问题。通过比较20年的X射线观测结果，1 E 0102.2-7219的膨胀率为0.100% ± 0.025% yr-1，推断年龄约为1000 yr，这与之前基于残骸中高速富氧光学细丝的研究所作的估计完全一致。与半径为6.4 pc的爆炸波估计从钱德拉图像，我们的膨胀率意味着爆炸波的速度约6000公里的s-1和电子温度范围2.5-45 keV，取决于无碰撞电子加热的程度。分析的钱德拉CCD光谱的直接postshock区域揭示了一个热等离子体的丰度和柱密度典型的小麦哲伦云和电子温度为0.4-1千电子伏。测得的电子温度明显低于上述合理的范围，只有当我们假设很大一部分冲击能量，而不是有助于加热冲击后的电子和离子，已经产生宇宙射线时，才能调和。
In this Letter, we use the unprecedented spatial resolution of the Chandra X-Ray Observatory to carry out, for the first time, a measurement of the postshock electron temperature and proper motion of a young supernova remnant, specifically to address questions about the postshock partition of energy among electrons, ions, and cosmic rays. The expansion rate, 0.100% ± 0.025% yr-1, and inferred age, ~1000 yr, of 1E 0102.2-7219, from a comparison of X-ray observations spanning 20 yr, are fully consistent with previous estimates based on studies of high-velocity oxygen-rich optical filaments in the remnant. With a radius of 6.4 pc for the blast wave estimated from the Chandra image, our expansion rate implies a blast-wave velocity of ~6000 km s-1 and a range of electron temperatures 2.5-45 keV, dependent on the degree of collisionless electron heating. Analysis of the Chandra CCD spectrum of the immediate postshock region reveals a thermal plasma with abundances and column density typical of the Small Magellanic Cloud and an electron temperature of 0.4-1 keV. The measured electron temperature is significantly lower than the plausible range above, which can be reconciled only if we assume that a significant fraction of the shock energy, rather than contributing to the heating of the postshock electrons and ions, has gone into generating cosmic rays.