Comparison of simulations and semi-analytical model for WDM subhalo mass functions

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Main Authors: Ono, Mizuki, Okamoto, Takashi, Ando, Shin'ichiro, Ishiyama, Tomoaki
Format: Preprint
Published: 2025
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author Ono, Mizuki
Okamoto, Takashi
Ando, Shin'ichiro
Ishiyama, Tomoaki
author_facet Ono, Mizuki
Okamoto, Takashi
Ando, Shin'ichiro
Ishiyama, Tomoaki
contents The Cold Dark Matter (CDM) model successfully explains large-scale structure formation, but challenges remain at smaller scales, leading to interest in Warm Dark Matter (WDM) as an alternative. The abundance of Milky Way subhalos depends on the mass of WDM particles, allowing constraints to be obtained by comparing observations and theoretical models. However, high-resolution simulations of heavier WDM particle masses are computationally demanding, making semi-analytical approaches valuable. In this study, we evaluate the ability of the Semi-Analytical Sub-Halo Inference Modeling for WDM (SASHIMI-W) to reproduce subhalo mass functions for heavier WDM particle masses. We perform high-resolution cosmological N-body simulations for CDM and WDM with particle masses of 1 keV, 3 keV, and 10 keV, and compare the ratio of the subhalo mass function between WDM and CDM cases. Our results show that SASHIMI-W successfully reproduces the simulation results over redshifts z = 0 to z = 2. Furthermore, both simulations and the semi-analytical model show a slight redshift dependence in the subhalo suppression ratio. However, a direct comparison of the differential subhalo mass functions shows discrepancies in the mid- and low-mass regions, suggesting that the tidal stripping effects implemented in SASHIMI-W may be too strong for WDM subhalos, or that the removal of spurious subhalos in the simulations is insufficient. These results validate the use of SASHIMI-W in constraining WDM properties, and highlight the need for refinements in both tidal effect modeling and spurious subhalo filtering to improve subhalo abundance predictions.
format Preprint
id arxiv_https___arxiv_org_abs_2505_15226
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Comparison of simulations and semi-analytical model for WDM subhalo mass functions
Ono, Mizuki
Okamoto, Takashi
Ando, Shin'ichiro
Ishiyama, Tomoaki
Cosmology and Nongalactic Astrophysics
The Cold Dark Matter (CDM) model successfully explains large-scale structure formation, but challenges remain at smaller scales, leading to interest in Warm Dark Matter (WDM) as an alternative. The abundance of Milky Way subhalos depends on the mass of WDM particles, allowing constraints to be obtained by comparing observations and theoretical models. However, high-resolution simulations of heavier WDM particle masses are computationally demanding, making semi-analytical approaches valuable. In this study, we evaluate the ability of the Semi-Analytical Sub-Halo Inference Modeling for WDM (SASHIMI-W) to reproduce subhalo mass functions for heavier WDM particle masses. We perform high-resolution cosmological N-body simulations for CDM and WDM with particle masses of 1 keV, 3 keV, and 10 keV, and compare the ratio of the subhalo mass function between WDM and CDM cases. Our results show that SASHIMI-W successfully reproduces the simulation results over redshifts z = 0 to z = 2. Furthermore, both simulations and the semi-analytical model show a slight redshift dependence in the subhalo suppression ratio. However, a direct comparison of the differential subhalo mass functions shows discrepancies in the mid- and low-mass regions, suggesting that the tidal stripping effects implemented in SASHIMI-W may be too strong for WDM subhalos, or that the removal of spurious subhalos in the simulations is insufficient. These results validate the use of SASHIMI-W in constraining WDM properties, and highlight the need for refinements in both tidal effect modeling and spurious subhalo filtering to improve subhalo abundance predictions.
title Comparison of simulations and semi-analytical model for WDM subhalo mass functions
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2505.15226