Future constraints on primordial black holes from XGIS-THESEUS

Abstract

Current observations allow primordial black holes (PBHs) in asteroid mass range 10¹⁷- 10²² g to constitute the entire dark matter energy density (barring a small mass range constrained by 21-cm observations). In this work, we explore the possibility of probing PBHs with masses 10¹⁷- 10¹⁹ g via the upcoming X/Gamma Ray Imaging Spectrometer (XGIS) telescope array on board the Transient High-Energy Sky and Early Universe Surveyor (THESEUS) mission. While our projected limits are comparable with those proposed in the literature for 10¹⁶ g <M_PBH<10¹⁷ g , we show that the XGIS-THESEUS mission can potentially provide the strongest bound for 10¹⁷ g <M_PBH≲3 ×10¹⁸ g for nonrotating PBHs. The bounds become more stringent by nearly an order of magnitude for maximally rotating PBHs in the mass range 5 ×10¹⁵ g <M_PBH≲10¹⁹ g .