Simulation Studies for the First Pathfinder of the CATCH Space Mission

• Published in: arXiv.org
• Main Authors: Huang, Yiming, Zhang, Juan, Lian Tao, Li, Zhengwei, Zhao, Donghua, Qian-Qing, Yin, Wen, Xiangyang, Xiao, Jingyu, Zhang, Chen, Zhang, Shuang-Nan, Xiong, Shaolin, Bu, Qingcui, Cang, Jirong, Cao, Dezhi, Chen, Wen, Ding, Siran, Gao, Min, Gao, Yang, Hou, Shujin, Jia, Liping, Ge, Jin, Li, Dalin, Li, Jinsong, Li, Panping, Li, Yajun, Liu, Xiaojing, Ma, Ruican, Pan, Xingyu, Qi, Liqiang, Rao, Jinhui, Sun, Xianfei, Tang, Qingwen, Tang, Ruijing, Wang, Yusa, Xu, Yibo, Yang, Sheng, Yang, Yanji, Yang, Yong, Zhang, Xuan, Zhang, Yueting, Zhou, Heng, Zhao, Kang, Zhao, Qingchang, Zhao, Shujie, Zhao, Zijian
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 23.02.2024
• Subjects: Charged particles; Cosmic x rays; Energy bands; Magnetic equator; Microsatellites; Physics - Instrumentation and Methods for Astrophysics; Satellite constellations; Sensitivity; Sensors; Simulation; Space missions; X-rays
• DOI: 10.48550/arxiv.2402.15275

The Chasing All Transients Constellation Hunters (CATCH) space mission is an intelligent constellation consisting of 126 micro-satellites in three types (A, B, and C), designed for X-ray observation with the objective of studying the dynamic universe. Currently, we are actively developing the first Pathfinder (CATCH-1) for the CATCH mission, specifically for type-A satellites. CATCH-1 is equipped with Micro Pore Optics (MPO) and a 4-pixel Silicon Drift Detector (SDD) array. To assess its scientific performance, including the effective area of the optical system, on-orbit background, and telescope sensitivity, we employ the Monte Carlo software Geant4 for simulation in this study. The MPO optics exhibit an effective area of \(41\) cm\(^2\) at the focal spot for 1 keV X-rays, while the entire telescope system achieves an effective area of \(29\) cm\(^2\) at 1 keV when taking into account the SDD detector's detection efficiency. The primary contribution to the background is found to be from the Cosmic X-ray Background. Assuming a 625 km orbit with an inclination of \(29^\circ\), the total background for CATCH-1 is estimated to be \(8.13\times10^{-2}\) counts s\(^{-1}\) in the energy range of 0.5--4 keV. Based on the background within the central detector and assuming a Crab-like source spectrum, the estimated ideal sensitivity could achieve \(1.9\times10^{-12}\) erg cm\(^{-2}\) s\(^{-1}\) for an exposure of 10\(^4\) s in the energy band of 0.5--4 keV. Furthermore, after simulating the background caused by low-energy charged particles near the geomagnetic equator, we have determined that there is no need to install a magnetic deflector.