Is dark matter self-interacting with a velocity-dependent cross section? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Is dark matter self-interacting with a velocity-dependent cross section?
Plain
If dark matter particles collide with each other, the centers of halos are smoothed into cores, and some cores later collapse into very dense centers. The collision strength may depend on speed, being larger in small galaxies than in clusters.
Precise · changed · core
Revision 1: Measure the self-interaction cross section per unit mass $\sigma/m$ ($\mathrm{cm}^2/\mathrm{g}$) as a function of relative velocity v from about $3e6\ \mathrm{cm}/\mathrm{s}$ (dwarfs) to $1e8\ \mathrm{cm}/\mathrm{s}$ (clusters) using dwarf rotation curves, satellite central densities, strong-lens perturbers, cluster cores and cluster mergers. Kaplinghat, Tulin and Yu (2016, PRL 116, 041302) infer about $2\ \mathrm{cm}^2/\mathrm{g}$ at galaxy scales and $0.1\ \mathrm{cm}^2/\mathrm{g}$ at cluster scales. An answer is a nonzero $\sigma/m(v)$ detected at more than $3\sigma$, or an upper bound below $0.1\ \mathrm{cm}^2/\mathrm{g}$ at dwarf velocities.
Revision 2: Measure the self-interaction cross section per unit mass $\sigma/m$ ($\mathrm{cm}^2/\mathrm{g}$) as a function of relative velocity v from about $3 \times 10^{6}\ \mathrm{cm}/\mathrm{s}$ (dwarfs) to $10^{8}\ \mathrm{cm}/\mathrm{s}$ (clusters) using dwarf rotation curves, satellite central densities, strong-lens perturbers, cluster cores and cluster mergers. Kaplinghat, Tulin and Yu (2016, PRL 116, 041302) infer about $2\ \mathrm{cm}^2/\mathrm{g}$ at galaxy scales and $0.1\ \mathrm{cm}^2/\mathrm{g}$ at cluster scales. An answer is a nonzero $\sigma/m(v)$ detected at more than $3\sigma$, or an upper bound below $0.1\ \mathrm{cm}^2/\mathrm{g}$ at dwarf velocities.
Settled by
A joint fit of dwarf, satellite, strong-lens and cluster data with self-interacting dark matter simulations that include gravothermal core collapse.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
open
Status note · changed
Revision 1: The dense $1e6\,M_{\mathrm{sun}}$ perturber found by gravitational imaging in JVAS B1938+666 (2025) has been interpreted as a core-collapsed self-interacting halo, an interpretation that is debated.
Revision 2: The dense $10^{6}\,M_{\mathrm{sun}}$ perturber found by gravitational imaging in JVAS B1938+666 (2025) has been interpreted as a core-collapsed self-interacting halo, an interpretation that is debated.
Posed since
2000

Decisions