超新星遗迹1987 A的高拍频色散谱分析
High-cadence Dispersed Spectral Analysis of Supernova Remnant 1987A
摘要：
我们对Chandra进行的超新星遗迹（SNR）1987 A观测的11个时期（2011年3月至2018年9月）的分散光谱数据进行了分析。这些观测是使用高能透射光栅（HETG）进行的，作为我们正在进行的SNR 1987 A钱德拉监测活动的一部分，其一阶色散光谱提供了比以前公布的0阶光谱更高的能量分辨率。我们的数据集具有每历元约50- 70 ks的中等曝光时间，涵盖了2011年3月和2018年3月进行的深度Chandra HETG观测（单个曝光> 200 ks）之间的时间段。这些数据具有比宽间隔深高分辨率光谱高得多的节奏，以总曝光时间为代价。虽然由于观测到的一阶光谱中的光子计数统计量较低，统计不确定性很大，但我们发现光谱模型参数通常与传播到致密内环以外的介质中的冲击波一致，如Frank等人2016所建议的那样。由于反向激波开始电离赤道环内部超新星喷出物的重元素，预计光谱拟合参数将随着激波气体的化学组成和物理性质的演变而变化。基于我们的宽带光谱模型拟合，我们发现，丰度值似乎是恒定的，在这段时间内。虽然我们的结果是有限的，由于光子统计，我们证明了分散HETG光谱分析，可以与我们的常规钱德拉监测观测SNR 1987 A的实用程序。
英文摘要：
We present an analysis of the dispersed spectral data from 11 epochs (March 2011 to September 2018) of supernova remnant (SNR) 1987A observations performed with Chandra. These observations were performed with the High Energy Transmission Grating (HETG) as part of our ongoing Chandra monitoring campaign of SNR 1987A, whose 1st-order dispersed spectrum provides a significantly greater energy resolution than the previously-published 0th-order spectrum. Our data sets with moderate exposure times of ~50-70ks per epoch cover the time period between deep Chandra HETG observations (with individual exposures >200ks) taken in March 2011 and March 2018. These data have a much higher cadence than the widely-spaced deep high-resolution spectra, at the expense of total exposure time. While statistical uncertainties are large due to low photon count statistics in the observed 1st-order spectra, we find that spectral model parameters are generally in line with the shock wave propagating into the medium beyond the dense inner ring, as suggested by Frank et al. 2016. As the reverse shock begins ionizing the heavier elements of the supernova ejecta interior to the equatorial ring, spectral fit parameters are expected to change as the chemical makeup and physical properties of the shocked gas evolve. Based on our broadband spectral model fits, we find that abundance values appear to be constant in this time period. While our results are somewhat limited due to photon statistics, we demonstrate the utility of the dispersed HETG spectral analysis that can be performed with our regular Chandra monitoring observations of SNR 1987A.
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