Gravitational microlensing by dressed primordial black holes

Abstract

The accretion of dark matter around the primordial black holes (PBHs) could lead to the formation of surrounding minihalos, whose mass can be several orders of magnitude higher than the central PBH mass. The gravitational microlensing produced by such dressed PBHs could be quite different from that of the bare PBHs, which may significantly affect the constraints on the PBH abundance. In this paper, we study the gravitational microlensing produced by dressed PBHs in detail. We find that all the microlensing effects by dressed PBHs have asymptotic behavior depending on the minihalo size, which can be used to predict the microlensing effects by comparing the halo size with the Einstein radius. When the minihalo radius and the Einstein radius are comparable, the effect of the density distribution of the halo is significant to the microlensing. Applying the stellar microlensing by dressed PBHs to the data of the Optical Gravitational Lensing Experiment and Subaru/HSC Andromeda observations, we obtain the improved constraints on the PBH abundance. It shows that the existence of dark matter minihalos surrounding PBHs can strengthen the constraints on the PBH abundance from stellar microlensing by several orders, and can shift the constraints to the well-known asteroid mass window where PBHs can constitute all the dark matter.

21 pages, 13 figures, add analysis of the wave optics effect and plots of the expected differential event rate, accepted for publication in JCAP

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• Strong lensing constraints on primordial black holes as a dark matter candidate
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• Coexistence Test of Primordial Black Holes and Particle Dark Matter from Diffractive Lensing
• Primordial regular black holes as all the dark matter. III. Covariant canonical quantum gravity models
• Axion star condensation around primordial black holes and microlensing limits
• New Light on Dark Extended Lenses with the Roman Space Telescope
• Toward More Realistic Mass Functions For Ultradense Dark Matter Halos
• Microlensing and event rate of static spherically symmetric wormhole
• Microlensing of dark matter models in the Milky Way
• Gravitational Lensing of Gravitational Waves from Astrophysical Sources: Theory, Detection, and Applications
• Novel Solar System Probes for Primordial Black Holes