Constraints on ultracompact minihalos from the extragalactic gamma-ray background observation

TL;DR

This paper refines constraints on ultracompact minihalos using updated gamma-ray background data, significantly improving previous limits and exploring potential unknown contributions beyond known astrophysical sources.

Contribution

It provides the most stringent constraints to date on UCMH abundance by incorporating recent gamma-ray measurements and comprehensive astrophysical modeling.

Findings

Constraints on UCMH abundance are 10-100 times tighter than previous limits.

Updated analysis using Fermi-LAT data improves sensitivity to UCMHs.

Potential to identify additional gamma-ray components beyond known sources.

Abstract

Ultracompact minihalo (UCMH) is a special type of dark matter halo with a very steep density profile which may form in the early universe seeded by an overdense region or a primordial black hole. Constraints on its abundance give valuable information on the power spectrum of primordial perturbation. In this work, we update the constraints on the UCMH abundance in the universe using the extragalactic gamma-ray background (EGB) observation. Comparing to previous works, we adopt the updated Fermi-LAT EGB measurement and derive constraints based on a full consideration of the astrophysical contributions. With these improvements, we place constraints on UCMH abundance 1-2 orders of magnitude better than previous results. With the background components considered, we can also attempt to search for possible additional components beyond the known astrophysical contributions.