论文标题
用Insight-HXMT的X射线泥土掩星的垂直大气密度剖面的测量
Measurement of the vertical atmospheric density profile from the X-ray Earth occultation of the Crab Nebula with Insight-HXMT
论文作者
论文摘要
在本文中，使用硬X射线调制望远镜（Insight-HXMT）研究了蟹状星云的X射线土掩星（XEO）。选择并分析了Insight-HXMT的低能X射线望远镜（LE）在2018年9月30日记录的指向观察数据。提取X射线土掩星过程中的灭绝光弯曲和光谱。建立了XEO LightCurve的正向模型，并预测了灯曲线的理论观察信号。大气密度模型的制造是在一定高度范围内的常用MSIS密度曲线的比例因子。为XEO LightCurve建模和大气密度检索开发了贝叶斯数据分析方法。模型参数的后验概率分布分别通过Markov链蒙特卡洛（MCMC）算法，该算法分别以基础函数和最佳拟合密度曲线为基础，并分别检索NRLMSIS-00模型和NRLMSIS 2.0模型。发现在105--200 km的高度范围内，检索到的密度曲线是NRLMSISE-00密度的88.8％，而基于XEOS方法将LightCurve拟合到1.0--2.5 KEV的NRLMSIS 2.0密度的109.7％。在95--125 km的高度范围内，检索到的密度曲线是NRLMSISE-00密度的81.0％，而NRLMSIS 2.0的密度的92.3％，通过将灯泡拟合到基于XEOS方法的2.5---6.0 KEV的能量范围。在85--110 km的高度范围内，检索到的密度曲线为NRLMSISE-00密度的87.7％，而基于XEOS方法的6.0---10.0 keV的能量范围将LightCurve拟合在6.0--10.0 KEV的能量范围内，NRLMSIS 2.0的密度的101.4％。这项研究表明，来自X射线天文卫星Insight-HXMT的XEO可以为研究上层大气的研究提供一种方法。
In this paper, the X-ray Earth occultation (XEO) of the Crab Nebula is investigated by using the Hard X-ray Modulation Telescope (Insight-HXMT). The pointing observation data on the 30th September, 2018 recorded by the Low Energy X-ray telescope (LE) of Insight-HXMT are selected and analyzed. The extinction lightcurves and spectra during the X-ray Earth occultation process are extracted. A forward model for the XEO lightcurve is established and the theoretical observational signal for lightcurve is predicted. The atmospheric density model is built with a scale factor to the commonly used MSIS density profile within a certain altitude range. A Bayesian data analysis method is developed for the XEO lightcurve modeling and the atmospheric density retrieval. The posterior probability distribution of the model parameters is derived through the Markov Chain Monte Carlo (MCMC) algorithm with the NRLMSISE-00 model and the NRLMSIS 2.0 model as basis functions and the best-fit density profiles are retrieved respectively. It is found that in the altitude range of 105--200 km, the retrieved density profile is 88.8% of the density of NRLMSISE-00 and 109.7% of the density of NRLMSIS 2.0 by fitting the lightcurve in the energy range of 1.0--2.5 keV based on XEOS method. In the altitude range of 95--125 km, the retrieved density profile is 81.0% of the density of NRLMSISE-00 and 92.3% of the density of NRLMSIS 2.0 by fitting the lightcurve in the energy range of 2.5--6.0 keV based on XEOS method. In the altitude range of 85--110 km, the retrieved density profile is 87.7% of the density of NRLMSISE-00 and 101.4% of the density of NRLMSIS 2.0 by fitting the lightcurve in the energy range of 6.0--10.0 keV based on XEOS method. This study demonstrates that the XEOS from the X-ray astronomical satellite Insight-HXMT can provide an approach for the study of the upper atmosphere.
