Strong constraints on primordial black hole dark matter from 16 years of INTEGRAL/SPI observations

We present a new analysis of the diffuse soft γ -ray emission toward the inner Galaxy as measured by the spectrometer aboard the INTEGRAL satellite (SPI) with 16 years of data taking. The analysis implements a spatial template fit of SPI data and an improved instrumental background model. We characterize the contribution of primordial black holes (PBH) as dark matter (DM) candidates evaporating into O (1 ) MeV photons by including, for the first time to our knowledge, the spatial distribution of their signal into the fitting procedure. No PBH signal is detected, and we set the strongest limit on PBH DM for masses up to 4 ×10¹⁷ g , significantly closing in to the so-called asteroid mass range.