Warm, not Fuzzy: Generalized Ultralight Dark Matter Limits from Milky Way Satellites

Fuente: arXiv
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Main Authors: Nadler, Ethan O., Amin, Mustafa A., Wechsler, Risa H., Delos, M. Sten, Benson, Andrew, Gluscevic, Vera
Format: Preprint
Published: 2026
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author Nadler, Ethan O.
Amin, Mustafa A.
Wechsler, Risa H.
Delos, M. Sten
Benson, Andrew
Gluscevic, Vera
author_facet Nadler, Ethan O.
Amin, Mustafa A.
Wechsler, Risa H.
Delos, M. Sten
Benson, Andrew
Gluscevic, Vera
contents We generalize lower limits on the dark matter (DM) particle mass $m$ derived from Milky Way (MW) satellite galaxy abundances to scenarios in which DM is an ultralight scalar field produced with a field power spectrum peaked at a subhorizon wavenumber $k_*$. In these models, the DM field free-streams similar to warm dark matter while also exhibiting significant small-scale wave interference effects. The resulting dimensionless density power spectrum shows two effects: (i) free-streaming suppression at $k_{\rm fs}\sim k_{\rm eq}/[(k_*/a_{\rm eq}m)\ln(a_{\rm eq}m/k_*)]$; (ii) Poisson-like enhancement related to wave interference, at $k\gtrsim10^{-2}k_*$, which saturates near the Jeans scale $k_{\rm J}\sim k_{\rm eq}/(k_*/a_{\rm eq}m)$. Comparing these predictions with established constraints on a free-streaming cutoff in the linear matter power spectrum from the MW satellite population, we obtain $m>6\times10^{-18}\,{\rm eV}\,(k_*/10^4\,{\rm Mpc}^{-1})$ for $k_*>10^4\,{\rm Mpc}^{-1}$ at 95\% confidence. For smaller $k_*$, Poisson-noise enhancement on MW satellite scales weakens the constraint, yielding $m>6\times10^{-18}\,{\rm eV}\,(k_*/10^4\,{\rm Mpc}^{-1})^2$ for $k_*<10^4\,{\rm Mpc}^{-1}$ at 95\% confidence.
format Preprint
id arxiv_https___arxiv_org_abs_2605_15371
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Warm, not Fuzzy: Generalized Ultralight Dark Matter Limits from Milky Way Satellites
Nadler, Ethan O.
Amin, Mustafa A.
Wechsler, Risa H.
Delos, M. Sten
Benson, Andrew
Gluscevic, Vera
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
We generalize lower limits on the dark matter (DM) particle mass $m$ derived from Milky Way (MW) satellite galaxy abundances to scenarios in which DM is an ultralight scalar field produced with a field power spectrum peaked at a subhorizon wavenumber $k_*$. In these models, the DM field free-streams similar to warm dark matter while also exhibiting significant small-scale wave interference effects. The resulting dimensionless density power spectrum shows two effects: (i) free-streaming suppression at $k_{\rm fs}\sim k_{\rm eq}/[(k_*/a_{\rm eq}m)\ln(a_{\rm eq}m/k_*)]$; (ii) Poisson-like enhancement related to wave interference, at $k\gtrsim10^{-2}k_*$, which saturates near the Jeans scale $k_{\rm J}\sim k_{\rm eq}/(k_*/a_{\rm eq}m)$. Comparing these predictions with established constraints on a free-streaming cutoff in the linear matter power spectrum from the MW satellite population, we obtain $m>6\times10^{-18}\,{\rm eV}\,(k_*/10^4\,{\rm Mpc}^{-1})$ for $k_*>10^4\,{\rm Mpc}^{-1}$ at 95\% confidence. For smaller $k_*$, Poisson-noise enhancement on MW satellite scales weakens the constraint, yielding $m>6\times10^{-18}\,{\rm eV}\,(k_*/10^4\,{\rm Mpc}^{-1})^2$ for $k_*<10^4\,{\rm Mpc}^{-1}$ at 95\% confidence.
title Warm, not Fuzzy: Generalized Ultralight Dark Matter Limits from Milky Way Satellites
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2605.15371