Disc-Based Estimation of the Local Dark Matter Density and Velocity Distribution in IllustrisTNG50
Abstract
We study the dark matter (DM) density and velocity distribution in the solar neighborhood of Milky Way-like galaxies using the TNG50-1 run of the IllustrisTNG simulation suite. Milky Way-like galaxies are selected according to both their halo mass and their bulge-to-total stellar mass ratio, and the solar-neighborhood region within each galaxy is identified from the positions and number density of stars, so that DM particles associated with the galactic disc are extracted while contributions from the halo component are suppressed. Averaging over the selected galaxies, we obtain a local DM density of ρ≃ 0.47±0.02 GeV cm−3, consistent with the range inferred from observations. The disc-based extraction gives a higher peak density, 0.41±0.02 GeV cm−3, than the value 0.34±0.02 GeV cm−3 from a simple distance-based extraction, probably because it excludes the low-density DM in the halo. The width of the density distribution, on the other hand, is nearly unchanged. The velocity distribution is well described by an isotropic Maxwellian with a peak velocity of about 226 km s−1, close to the value assumed in the standard halo model. The differences in the density and velocity distributions between our disc-based and simple distance-based extractions are not so large as to significantly affect the interpretation of direct-detection experiments.
Related
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BibTeX
@misc{chujo2026discbased,
title = {{Disc-Based Estimation of the Local Dark Matter Density and Velocity Distribution in IllustrisTNG50}},
author = {Hatsume Chujo and Shogo Masaki and Keiko I. Nagao and Takuho Nakabayashi},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.02185},
eprint = {2609.02185},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.02185},
}
RIS
TY - UNPB
TI - Disc-Based Estimation of the Local Dark Matter Density and Velocity Distribution in IllustrisTNG50
AU - Hatsume Chujo
AU - Shogo Masaki
AU - Keiko I. Nagao
AU - Takuho Nakabayashi
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2609.02185
UR - https://arxiv.org/abs/2609.02185
AB - We study the dark matter (DM) density and velocity distribution in the solar neighborhood of Milky Way-like galaxies using the TNG50-1 run of the IllustrisTNG simulation suite. Milky Way-like galaxies are selected according to both their halo mass and their bulge-to-total stellar mass ratio, and the solar-neighborhood region within each galaxy is identified from the positions and number density of stars, so that DM particles associated with the galactic disc are extracted while contributions from the halo component are suppressed. Averaging over the selected galaxies, we obtain a local DM density of ρ≃ 0.47±0.02 GeV cm^−3, consistent with the range inferred from observations. The disc-based extraction gives a higher peak density, 0.41±0.02 GeV cm^−3, than the value 0.34±0.02 GeV cm^−3 from a simple distance-based extraction, probably because it excludes the low-density DM in the halo. The width of the density distribution, on the other hand, is nearly unchanged. The velocity distribution is well described by an isotropic Maxwellian with a peak velocity of about 226 km s^−1, close to the value assumed in the standard halo model. The differences in the density and velocity distributions between our disc-based and simple distance-based extractions are not so large as to significantly affect the interpretation of direct-detection experiments.
ER -