Background model for the high-energy telescope of Insight-HXMT
Background model for the high-energy telescope of Insight-HXMT
复制标题
DOI：
10.1016/j.jheap.2020.04.002
复制
发表时间：
2020-05
期刊：
影响因子：
--
通讯作者：
Jinyuan Liao;Shu Zhang;Xue-Feng Lu;Juan Zhang;Gang Li;Z. Chang;Yu-Peng Chen;M. Ge;
中科院分区：
文献类型：
--
作者：
Jinyuan Liao;Shu Zhang;Xue-Feng Lu;Juan Zhang;Gang Li;Z. Chang;Yu-Peng Chen;M. Ge;
准确的背景估计对于天体物理学中的光谱和时间分析至关重要。在这项工作中，我们为硬X射线调制望远镜（称为Insight-HXMT）的高能望远镜（HE）构建了在轨背景模型。基于Insight-HXMT/HE两年的空白天空观测，我们首先研究了背景的基本属性，发现背景光谱形状和强度在不同的地理位置都有长期的演化。然后将整个地球划分为小网格，每个网格在地理坐标系中的典型面积为 5× 5 平方度。对于每个网格，用一个经验函数来描述背景光谱每个通道的长期演化；背景的强度可以是可变的，并且通过测量盲检测器的当前通量引入修正因子来解释这种可变性。对于给定的指向观测，背景模型是通过对每个轨道上卫星轨道经过的网格进行积分来完成的。这样的背景模型通过空白天空观测和一系列天体源观测活动进行了测试。结果显示，在 8 ks 的典型曝光下，背景能谱 (26–100 keV) 的平均系统误差为 1.5%，背景光曲线估计 (30–150 keV) 的平均系统误差 < 3%。因此，本文介绍的背景模型被包含在Insight-HXMT软件中，作为专门用于光谱和时间分析的标准部分。
Accurate background estimation is essential for spectral and temporal analysis in astrophysics. In this work, we construct the in-orbit background model for the High-Energy Telescope (HE) of the Hard X-ray Modulation Telescope (dubbed as Insight-HXMT). Based on the two-year blank sky observations of Insight-HXMT/HE, we first investigate the basic properties of the background and find that both the background spectral shape and intensity have long-term evolution at different geographical sites. The entire earth globe is then divided into small grids, each with a typical area of 5× 5 square degrees in geographical coordinate system. For each grid, an empirical function is used to describe the long-term evolution of each channel of the background spectrum; the intensity of the background can be variable and a modification factor is introduced to account for this variability by measuring the contemporary flux of the blind detector. For a given pointing observation, the background model is accomplished by integrating over the grids that are passed by the track of the satellite in each orbit. Such a background model is tested with both the blank sky observations and campaigns for observations of a series of celestial sources. The results show an average systematic error of 1.5% for the background energy spectrum (26–100 keV) under a typical exposure of 8 ks, and< 3% for background light curve estimation (30–150 keV). Therefore, the background model introduced in this paper is included in the Insight-HXMT software as a standard part specialized for both spectral and temporal analyses.