Constraining primordial black hole abundance with Insight-HXMT

TL;DR

This study uses data from Insight-HXMT to refine constraints on primordial black holes in the mass range of 2×10^{16} to 5×10^{17} grams, especially under a power-law spectrum model, improving existing limits on their contribution to dark matter.

Contribution

It introduces a novel analysis of Insight-HXMT data with different astrophysical models, significantly tightening constraints on PBHs in the specified mass range, especially for masses above 10^{17} grams.

Findings

Insight-HXMT enhances constraints under the power-law model.

Constraints on PBHs as dark matter reach 4×10^{17} grams.

No advantage found in the first two observational scenarios.

Abstract

Primordial black holes (PBHs) are a major candidate for dark matter and they have been extensively constrained across most mass ranges. However, PBHs in the mass range of $10^{17}$ - $10^{21}$ g remain a viable explanation for all dark matter. In this work, we use observational data from the Hard X-ray Modulation Telescope (Insight-HXMT) to refine constraints on PBHs within the mass range of $2\times10^{16}$ - $5\times10^{17}$ g. Our analysis explores three scenarios: directly using observational data, incorporating the astrophysical background model (ABM), and employing the power-law spectrum with an exponential cutoff. Our results indicate that although Insight-HXMT does not have an advantage in the first two scenarios, when considering the power-law model, its exceptional sensitivity in the hard X-ray regime and sufficiently high upper energy limit significantly strengthen the constraints on PBHs with masses greater than $10^{17}$ g compared to previous limits. Furthermore, the exclusion limit for PBHs as dark matter has reached $4\times10^{17}$ g, which is comparable to the current threshold.