Massive prompt cusps: A new signature of warm dark matter

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1. Verfasser: Delos, M. Sten
Format: Preprint
Veröffentlicht: 2023
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author Delos, M. Sten
author_facet Delos, M. Sten
contents Every dark matter halo and subhalo is expected to have a prompt $ρ\propto r^{-1.5}$ central density cusp, which is a relic of its condensation out of the smooth mass distribution of the early universe. The sizes of these prompt cusps are linked to the scales of the peaks in the initial density field from which they formed. In warm dark matter (WDM) models, the smoothing scale set by free streaming of the dark matter can result in prompt cusps with masses of order $10^7$ M$_\odot$. We show that WDM models with particle masses ranging from 2 to 6 keV predict prompt cusps that could detectably alter the observed kinematics of Local Group dwarf galaxies. Thus, prompt cusps present a viable new probe of WDM. A prompt cusp's properties are highly sensitive to when it formed, so prospects can be improved with a better understanding of when the haloes of the Local Group dwarfs originally formed. Tidal stripping can also affect prompt cusps, so constraints on satellite galaxy orbits can further tighten WDM inferences.
format Preprint
id arxiv_https___arxiv_org_abs_2302_03040
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Massive prompt cusps: A new signature of warm dark matter
Delos, M. Sten
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
Every dark matter halo and subhalo is expected to have a prompt $ρ\propto r^{-1.5}$ central density cusp, which is a relic of its condensation out of the smooth mass distribution of the early universe. The sizes of these prompt cusps are linked to the scales of the peaks in the initial density field from which they formed. In warm dark matter (WDM) models, the smoothing scale set by free streaming of the dark matter can result in prompt cusps with masses of order $10^7$ M$_\odot$. We show that WDM models with particle masses ranging from 2 to 6 keV predict prompt cusps that could detectably alter the observed kinematics of Local Group dwarf galaxies. Thus, prompt cusps present a viable new probe of WDM. A prompt cusp's properties are highly sensitive to when it formed, so prospects can be improved with a better understanding of when the haloes of the Local Group dwarfs originally formed. Tidal stripping can also affect prompt cusps, so constraints on satellite galaxy orbits can further tighten WDM inferences.
title Massive prompt cusps: A new signature of warm dark matter
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2302.03040