Lyman-$α$ Forest Constraint on Dark Matter from Dark Sector Decay

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Hauptverfasser: Zhao, Si-Yuan, Dai, Yi-Cheng, Liao, Wei, Lu, Yi-Song
Format: Preprint
Veröffentlicht: 2026
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author Zhao, Si-Yuan
Dai, Yi-Cheng
Liao, Wei
Lu, Yi-Song
author_facet Zhao, Si-Yuan
Dai, Yi-Cheng
Liao, Wei
Lu, Yi-Song
contents By exploiting small-scale structure formation probed by Lyman-$α$ forest observations, we study constraints on a model of dark matter from dark sector decay. We compute the phase space distribution of the dark matter and the linear matter power spectrum. We map the non-thermal dark matter distribution in this dark matter model to an approximate thermal warm dark matter distribution, and use this approximation to obtain a constraint from the Lyman-$α$ forest observation. We combine the latest Lyman-$α$ forest bounds with the constraint from the Big Bang Nucleosynthesis. As these two probes offer highly complementary constraints, we impose strong limits on sub-GeV dark matter. Consequently, masses lighter than $\sim 10^{-1}$ GeV are excluded, thereby significantly limiting the allowed parameter space. More broadly, our findings demonstrate the utility of small-scale structure observations in testing non-thermal dark matter paradigms, offering valuable insights for exploring a wider class of late-time decay models.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24331
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Lyman-$α$ Forest Constraint on Dark Matter from Dark Sector Decay
Zhao, Si-Yuan
Dai, Yi-Cheng
Liao, Wei
Lu, Yi-Song
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
By exploiting small-scale structure formation probed by Lyman-$α$ forest observations, we study constraints on a model of dark matter from dark sector decay. We compute the phase space distribution of the dark matter and the linear matter power spectrum. We map the non-thermal dark matter distribution in this dark matter model to an approximate thermal warm dark matter distribution, and use this approximation to obtain a constraint from the Lyman-$α$ forest observation. We combine the latest Lyman-$α$ forest bounds with the constraint from the Big Bang Nucleosynthesis. As these two probes offer highly complementary constraints, we impose strong limits on sub-GeV dark matter. Consequently, masses lighter than $\sim 10^{-1}$ GeV are excluded, thereby significantly limiting the allowed parameter space. More broadly, our findings demonstrate the utility of small-scale structure observations in testing non-thermal dark matter paradigms, offering valuable insights for exploring a wider class of late-time decay models.
title Lyman-$α$ Forest Constraint on Dark Matter from Dark Sector Decay
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2603.24331