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arXiv 1306.3994astro-ph.HEastro-ph.GA
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超新星遗迹RCW 86中H α细丝的自行

Proper Motions of H-alpha filaments in the Supernova Remnant RCW 86

E. A. Helder, J. Vink, A. Bamba, J. A. M. Bleeker, D. N. Burrows, P. Ghavamian, R. Yamazaki

摘要:

本文基于VLT/FORS 2在2007年和2010年进行的光学观测,对超新星遗迹RCW 86(MSH 14-63,G315.4-2.3)的东部激波区进行了自行研究。对于东北部和东南部地区,我们测量到H-α细丝的平均自行为0.10 +/- 0.02 arcsec/yr,相当于在2.5kpc时1200 +/- 200 km/s。在导出的自行中有很大的变化,表明冲击波速度从略低于700 km/s到高于2200 km/s不等。光学自行低于以前测得的东北地区的X射线自行。新的测量结果与先前测量的质子温度2.3 +/- 0.3 keV一致,假设没有宇宙射线加速。然而,在不确定性的范围内,适度有效(<27%)的冲击加速仍然是可能的。光学自行和质子温度的组合排除了RCW 86距离小于1.5kpc的可能性。东北部和东南部自行的相似性是特殊的,因为这两个地区的密度和X射线发射特性不同。东北部地区的密度较低,X射线辐射是同步辐射为主,这表明冲击波的速度应该高于东南部,热X射线为主,区域。一个可能的解决方案是,H-α发射丝偏向于密度更高的区域,具有较低的冲击速度。另外,在东北部,在过去的200年里,激波速度可能已经迅速下降,X射线同步辐射是激波速度较高时期的余辉。

英文摘要:

We present a proper motion study of the eastern shock-region of the supernova remnant RCW 86 (MSH 14-63, G315.4-2.3), based on optical observations carried out with VLT/FORS2 in 2007 and 2010. For both the northeastern and southeastern regions, we measure an average proper motion of H-alpha filaments of 0.10 +/- 0.02 arcsec/yr, corresponding to 1200 +/- 200 km/s at 2.5kpc. There is substantial variation in the derived proper motions, indicating shock velocities ranging from just below 700 km/s to above 2200 km/s. The optical proper motion is lower than the previously measured X-ray proper motion of northeastern region. The new measurements are consistent with the previously measured proton temperature of 2.3 +/- 0.3 keV, assuming no cosmic-ray acceleration. However, within the uncertainties, moderately efficient (< 27 per cent) shock acceleration is still possible. The combination of optical proper motion and proton temperature rule out the possibility that RCW 86 has a distance less than 1.5kpc. The similarity of the proper motions in the northeast and southeast is peculiar, given the different densities and X-ray emission properties of the regions. The northeastern region has lower densities and the X-ray emission is synchrotron dominated, suggesting that the shock velocities should be higher than in the southeastern, thermal X-ray dominated, region. A possible solution is that the H-alpha emitting filaments are biased toward denser regions, with lower shock velocities. Alternatively, in the northeast the shock velocity may have decreased rapidly during the past 200yr, and the X-ray synchrotron emission is an afterglow from a period when the shock velocity was higher.

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