The abundance of primordial black holes from the global 21cm signal and extragalactic gamma-ray background

Abstract

Primordial black holes (PBHs) formed in the early Universe can accret dark matter particles due to gravity and form ultracompact minihalos (UCMHs). The theoretical researches and simulations have shown that the density profile of dark matter in UCMHs is in the form of $\rho (r)\sim r^{-2.25}$. Compared with the popular dark matter halo model, e.g. NFW model, dark matter annihilation rate is larger in UCMHs. Considering dark matter annihilation, there is a maximum core density ${\rho }_{\max }$ in UCMHs which has been treated independent on redshift. While in this work, we point out that ${\rho }_{\max }$ depends on redshift and dark matter annihilation rate in UCMHs also changes with time. We re-investigate the $\gamma$-ray flux from UCMHs due to dark matter annihilation and focus on their contributions to the extragalactic gamma-ray background (EGB). Utilizing the EGB data of Fermi, the constraints on the abundance of PBHs are derived, ${\Omega }_{\mathrm{PBH},\mathrm{EGB}}\lesssim 2\times 10^{-8}$. Motivated by the recent observations of global 21cm signals by the EDGES experiment, we investigate the influences of dark matter annihilation in UCMHs on global 21cm signals and derive the constraints on the abundance of PBHs, ${\Omega }_{\mathrm{PBH},21cm}\lesssim 2\times 10^{-10}$. The derived constraints are valid for mass range of $10^{-6}{M}_{\odot }\lesssim M_{\mathrm{PBH}}\lesssim 10^3{M}_{\odot }$.

8 pages, 2 figures. Eur.Phys.J.Plus 135, 690 (2020). (https://rdcu.be/b6H7X)

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Cited by in corpus (11)

• Constraining primordial black holes as dark matter using the global 21-cm signal with X-ray heating and excess radio background
• 21-cm constraints on spinning primordial black holes
• Constraining Mixed Dark-Matter Scenarios of WIMPs and Primordial Black Holes from CMB and 21-cm observations
• Constraining spinning primordial black holes with global 21-cm signal
• Primordial Black Hole Dark Matter in the Context of Extra Dimensions
• Primordial black hole dark matter in the presence of p-wave WIMP annihilation
• Impact of radiation from primordial black holes on the 21-cm angular-power spectrum in the dark ages
• Constraints on ultracompact minihalos from the extragalactic gamma-ray background observation
• Radio bounds on the mixed dark matter scenarios of primordial black holes and WIMPs
• Cosmological abundance of primordial black holes in mixed dark matter scenarios incorporating Kaluza-Klein dark matter
• Sensitivities on non-spinning and spinning primordial black hole dark matter with global 21 cm troughs