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

TL;DR

This study analyzes 16 years of INTEGRAL/SPI data to search for primordial black hole dark matter signals in the gamma-ray spectrum, setting new constraints on their abundance in the asteroid mass range.

Contribution

It introduces a novel spatial template fitting method that incorporates the distribution of primordial black hole signals, improving constraints on their dark matter role.

Findings

No primordial black hole signals detected.

Set the strongest limits on PBH dark matter for masses up to 4×10^{17} g.

Significantly constrains the asteroid mass range of PBHs.

Abstract

We present a new analysis of the diffuse soft $\gamma$-ray emission towards 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 $\mathcal{O}$(1) MeV photons by including, for the first time, 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 $4 \times 10^{17}$ g, significantly closing in into the so-called asteroid mass range.