Gamma-Ray Burst Observations by the HEPD-01 Detector on Board the CSES-01 Satellite and Future Perspectives

Cosmic impulsive gamma-ray signals, namely Gamma-Ray Bursts (GRBs), are extremely intense electromagnetic events revealed by high-energy photon detectors aboard satellites orbiting in Low-Earth Orbits (LEO), Highly Excentric Orbits (HEO) or as part of the International Planetary Network (IPN). The High-Energy Particle Detector (HEPD-01), operational since 2018 on a LEO, detected five strong events, namely GRB190114C, GRB190305A, GRB190928A, GRB200826B and GRB211211A, between 2019 and 2021. For each event, the HEPD-01 electron-flux time profile has shown a remarkable similarity - in spite of the different energy ranges - with the light curve provided by dedicated gamma-ray instruments like IBIS-PICsIT and SPI-ACS on board the INTEGRAL satellite. Via a Monte Carlo simulation, we have characterized HEPD-01 operated as a gamma-ray detector, which provides a good sensitivity to gamma-rays in the energy range between 300 keV and 50 MeV. In this way, for each GRB, we have derived the light curve, peak intensity and fluence, compared to the one extrapolated in the same energy interval from the Konus-Wind observations. The reported results provide a valuable contribution to the single GRB characterization and are very promising in view of the launch of HEPD-02 on board the CSES-02 satellite in late 2024. Indeed, unlike HEPD-01, the second-generation detector will be equipped with a dedicated trigger system for gamma-ray detection, which is likely to allow the future mission to contribute to a wider, real-time GRB alert program.