Are ultrashort microlensing events caused by planets or primordial black holes? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Are ultrashort microlensing events caused by planets or primordial black holes?
Plain
Surveys watching millions of stars see a few brightenings lasting less than a day, caused by passing objects about as heavy as the Earth. They are usually attributed to planets drifting free of any star, but primordial black holes would produce identical events.
Precise · changed · core
Revision 1: OGLE bulge data contain 6 ultrashort events that Niikura et al. (2019, arXiv:1901.07120) reproduce with Earth-mass PBHs forming about a percent of dark matter, while MOA (Sumi et al. 2023, arXiv:2303.08280) attributes such events to about 21 free-floating planets per star. Determine $f_{\mathrm{PBH}} = \Omega_{\mathrm{PBH}} / \Omega_{c}$ for $M = 1e-7\ \text{to}\ 1e-5\ M_{\mathrm{sun}}$ ($2e26\ \text{to}\ 2e28\ \mathrm{g}$) by separating lens populations through event-rate dependence on direction (bulge, disk, halo, lines of sight to the LMC and M31) and through lens-distance information.
Revision 2: OGLE bulge data contain 6 ultrashort events that Niikura et al. (2019, arXiv:1901.07120) reproduce with Earth-mass PBHs forming about a percent of dark matter, while MOA (Sumi et al. 2023, arXiv:2303.08280) attributes such events to about 21 free-floating planets per star. Determine $f_{\mathrm{PBH}} = \Omega_{\mathrm{PBH}} / \Omega_{c}$ for $M = 10^{-7}\ \text{to}\ 10^{-5}\ M_{\mathrm{sun}}$ ($2 \times 10^{26}\ \text{to}\ 2 \times 10^{28}\ \mathrm{g}$) by separating lens populations through event-rate dependence on direction (bulge, disk, halo, lines of sight to the LMC and M31) and through lens-distance information.
Settled by
Nancy Grace Roman Space Telescope microlensing statistics with parallax for short events, compared between the bulge and halo-dominated lines of sight.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
open
Status note · changed
Revision 1: Mroz et al. (2024, Nature 632, 749) bound $f_{\mathrm{PBH}} < 0.1$ for $1.3e-5 \text{ to } 860\,M_{\mathrm{sun}}$ toward the LMC, leaving the Earth-mass range less constrained.
Revision 2: Mroz et al. (2024, Nature 632, 749) bound $f_{\mathrm{PBH}} < 0.1$ for $1.3 \times 10^{-5} \text{ to } 860\,M_{\mathrm{sun}}$ toward the LMC, leaving the Earth-mass range less constrained.
Posed since
2019

Decisions