Can asteroid-mass primordial black holes be all the dark matter? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Can asteroid-mass primordial black holes be all the dark matter?
Plain
Black holes could have formed directly from dense regions in the very early universe. Black holes weighing as much as an asteroid are too small to be seen by most tests, so they could still make up all the dark matter.
Precise · changed · core
Revision 1: For primordial black holes with masses $M = 1e17 \text{ to } 1e22\,\mathrm{g}$, no current constraint excludes a dark-matter fraction $f_{\mathrm{PBH}} = \Omega_{\mathrm{PBH}} / \Omega_c = 1$. Determine whether $f_{\mathrm{PBH}} = 1$ is allowed anywhere in this window, via detection (Hawking evaporation products at the light end, femtolensing or microlensing of stars and gamma-ray bursts, dynamical capture in stars) or exclusion of $f_{\mathrm{PBH}} = 1$ across the whole window for monochromatic and extended mass functions.
Revision 2: For primordial black holes with masses $M = 10^{17} \text{ to } 10^{22}\,\mathrm{g}$, no current constraint excludes a dark-matter fraction $f_{\mathrm{PBH}} = \Omega_{\mathrm{PBH}} / \Omega_c = 1$. Determine whether $f_{\mathrm{PBH}} = 1$ is allowed anywhere in this window, via detection (Hawking evaporation products at the light end, femtolensing or microlensing of stars and gamma-ray bursts, dynamical capture in stars) or exclusion of $f_{\mathrm{PBH}} = 1$ across the whole window for monochromatic and extended mass functions.
Settled by · changed · core
Revision 1: Microlensing surveys and MeV $\gamma$-ray observations sensitive enough to probe $f_{\mathrm{PBH}} < 1$ throughout 1e17 to 1e22 g.
Revision 2: Microlensing surveys and MeV $\gamma$-ray observations sensitive enough to probe $f_{\mathrm{PBH}} < 1$ throughout $10^{17}$ to $10^{22}$ g.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
open
Status note · changed
Revision 1: 2026 reviews still list $1e17\ \text{to}\ 1e22\,\mathrm{g}$ as a window where $f_{\mathrm{PBH}} = 1$ is allowed.
Revision 2: 2026 reviews still list $10^{17}\ \text{to}\ 10^{22}\,\mathrm{g}$ as a window where $f_{\mathrm{PBH}} = 1$ is allowed.
Posed since
(empty)

Decisions