Extracting Dark-Matter Velocities from Halo Masses: A Reconstruction Conjecture
| Autor: | Keith R. Dienes, Fei Huang, Jeff Kost, Kevin Manogue, Brooks Thomas |
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| Rok vydání: | 2021 |
| Předmět: | |
| DOI: | 10.48550/arxiv.2101.10337 |
| Popis: | Increasing attention has recently focused on non-traditional dark-matter production mechanisms which result in primordial dark-matter velocity distributions with highly non-thermal shapes. In this paper, we undertake an assessment of how the detailed shape of a general dark-matter velocity distribution impacts structure formation in the non-linear regime. In particular, we investigate the impact on the halo-mass and subhalo-mass functions, as well as on astrophysical observables such as satellite and cluster-number counts. We find that many of the standard expectations no longer hold in situations in which this velocity distribution takes a highly non-trivial, even multi-modal shape. For example, we find that the nominal free-streaming scale alone becomes insufficient to characterize the effect of free-streaming on structure formation. In addition, we propose a simple one-line conjecture which can be used to "reconstruct" the primordial dark-matter velocity distribution directly from the shape of the halo-mass function. Although our conjecture is completely heuristic, we show that it successfully reproduces the salient features of the underlying dark-matter velocity distribution even for non-trivial distributions which are highly non-thermal and/or multi-modal, such as might occur for non-minimal dark sectors. Moreover, since our approach relies only on the halo-mass function, our conjecture provides a method of probing dark-matter properties even for scenarios in which the dark and visible sectors interact only gravitationally. Comment: 23 pages, LaTeX, 10 figures. Results extended and new discussion added |
| Databáze: | OpenAIRE |
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