TY - JOUR
T1 - Extracting dark-matter velocities from halo masses
T2 - A reconstruction conjecture
AU - Dienes, Keith R.
AU - Huang, Fei
AU - Kost, Jeff
AU - Manogue, Kevin
AU - Thomas, Brooks
N1 - Funding Information:
We would like to thank K. Abazajian, K. Boddy, and Z. Zhai for discussions. K. M. wishes to thank the EXCEL Scholars Program for Undergraduate Research at Lafayette College, which helped to facilitate this research. The research activities of K. R. D. are supported in part by the Department of Energy under Grant No. DE-FG02-13ER41976 (DE-SC0009913) and by the National Science Foundation through its employee IR/D program. F. H. is supported in part by the National Natural Science Foundation of China (NSFC) under Grants No. 11690022, No. 12047503, No. 11875003, and No. 12022514 and is also supported by the Strategic Priority Research Program and Key Research Program of Frontier Science of the Chinese Academy of Sciences under Grants No. XDB21010200, No. XDB23000000, and No. ZDBS-LY-7003. The research activities of J. K. are supported in part by the Science and Technology Research Council (STFC) under the Consolidated Grant No. ST/T00102X/1. The research activities of K. M. and B. T. are supported in part by the National Science Foundation under Grants No. PHY-1720430 and No. PHY-2014104. The opinions and conclusions expressed herein are those of the authors and do not represent any funding agencies.
Publisher Copyright:
© 2022 American Physical Society. American Physical Society.
PY - 2022/10/15
Y1 - 2022/10/15
N2 - Increasing attention has recently focused on nontraditional dark-matter production mechanisms which result in primordial dark-matter velocity distributions with highly nonthermal 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 nonlinear 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 nontrivial, even multimodal 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 nontrivial distributions which are highly nonthermal and/or multimodal, such as might occur for nonminimal 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.
AB - Increasing attention has recently focused on nontraditional dark-matter production mechanisms which result in primordial dark-matter velocity distributions with highly nonthermal 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 nonlinear 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 nontrivial, even multimodal 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 nontrivial distributions which are highly nonthermal and/or multimodal, such as might occur for nonminimal 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.
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U2 - 10.1103/PhysRevD.106.083506
DO - 10.1103/PhysRevD.106.083506
M3 - Article
AN - SCOPUS:85140252772
SN - 2470-0010
VL - 106
JO - Physical Review D
JF - Physical Review D
IS - 8
M1 - 083506
ER -