Simulation studies for the first pathfinder of the CATCH space mission
Abstract
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 cm2 at the focal spot for 1 keV X-rays, while the entire telescope system achieves an effective area of 29 cm2 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∘, the total background for CATCH-1 is estimated to be 8.13 ×10-2 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 ×10-12 erg cm-2 s-1 for an exposure of 104 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.
- Publication:
-
Experimental Astronomy
- Pub Date:
- February 2024
- DOI:
- 10.1007/s10686-024-09924-0
- arXiv:
- arXiv:2402.15275
- Bibcode:
- 2024ExA....57....3H
- Keywords:
-
- CATCH;
- X-ray telescope;
- Geant4 simulation;
- Effective area;
- Background;
- Sensitivity;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- doi:10.1007/s10686-024-09924-0