20-Year INTEGRAL/IBIS Data Tightens Limits on Asteroid-Mass Primordial Black Holes as Dark Matter
The preprint presents the first joint spectral-morphological search for PBH evaporation signals in 20-year INTEGRAL/IBIS data. It derives competitive limits on the PBH dark matter fraction while identifying electron propagation as the main uncertainty. The work positions hard X-ray observations as a complementary channel for testing asteroid-mass PBHs.
Researchers modeled the Galactic hard X-ray background by incorporating inverse Compton emission from cosmic-ray electrons, unresolved accreting white dwarfs, and a possible contribution from Hawking-evaporating PBHs. The 20-year INTEGRAL/IBIS dataset enabled joint use of spatial morphology and spectral shape to separate a PBH signal from astrophysical foregrounds more effectively than spectrum-only methods. Constraints were derived for both monochromatic and extended mass functions, including rotating PBHs, yielding competitive upper limits on the PBH dark matter fraction.
The dominant uncertainty arises from propagation modeling of low-energy electrons and positrons rather than from the Galactic dark matter density profile. This limits the robustness of the signal prediction but still produces bounds that complement gamma-ray and neutrino searches. The approach demonstrates that hard X-ray observations can serve as an independent probe of evaporating PBHs when background components are treated self-consistently.
Cross-checks with Fermi-LAT diffuse emission data and upcoming eROSITA analyses could test the same electron population under different energy regimes. Refining cosmic-ray propagation parameters with new low-energy measurements would directly strengthen the PBH constraints by reducing the leading systematic.
Koechler et al.: Refined propagation models from new low-energy cosmic-ray data will reduce the dominant uncertainty and push PBH fraction limits below 5% for 10^17 g masses within three years.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2609.12044)
- [2]Supporting Source(https://arxiv.org/abs/2306.00052)