Which Milky Way Streams Make the Best Dark Matter Detectors?
Abstract
The abundance and properties of low-mass dark matter subhalos can be inferred by measuring the density and velocity structure of stellar streams, testing physical models of dark matter. Which streams make the most promising dark matter detectors, and which subhalos would they encounter? We use the semi-analytic model galacticus to simulate the Milky Way's dark subhalos, including tidal stripping under the influence of the galactic disk. Deriving stream initial conditions that best match present-day observations, we forecast subhalo encounters for 24 globular cluster streams around the Milky Way. Over their lifetimes, the 10 most perturbed streams are predicted to each experience ≈ 2-$12$ significant subhalo encounters with velocity kicks vkick > 0.1 km s−1. Jet, AAU, GD-1, and Palomar 5 lead the list, with Jet encountering twice the subhalos of any other stream. The subhalos that encounter streams have been tidally stripped to $1−20\%$ of their peak mass and are twice as compact as previous works have assumed. A spectroscopic survey of streams with sub-km s−1 precision could reveal the influence of dark subhalos below the threshold of galaxy formation. Predicting the abundance and scatter of low-mass subhalos that reach the inner galaxy remains a dominant uncertainty in connecting stellar streams to models of dark matter.
Related
- Milky Way White Dwarfs as Inelastic Dark Matter Detectors
- Prospects for Near-Far Constraints on Reionization from Simulated LSST Observations of Milky Way Dwarf Galaxies and Stellar Streams
- The multiple origins of spurs in stellar streams: a challenge for dark matter diagnostics
- Dark matter density profiles of the Milky Way satellite population: Reconciling simulations and observations
- Dark Matter in the Galaxy: Insights from the Dynamics of Stellar Streams
BibTeX
@misc{chandra2026which,
title = {{Which Milky Way Streams Make the Best Dark Matter Detectors?}},
author = {Vedant Chandra and Charlie Conroy and Risa Wechsler and Ana Bonaca and Andrew Benson and Jacob Nibauer and Tara Dacunha and Philip Mansfield and Paul Menker and Anya Phillips},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.00456},
eprint = {2610.00456},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.00456},
}
RIS
TY - UNPB
TI - Which Milky Way Streams Make the Best Dark Matter Detectors?
AU - Vedant Chandra
AU - Charlie Conroy
AU - Risa Wechsler
AU - Ana Bonaca
AU - Andrew Benson
AU - Jacob Nibauer
AU - Tara Dacunha
AU - Philip Mansfield
AU - Paul Menker
AU - Anya Phillips
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.00456
UR - https://arxiv.org/abs/2610.00456
AB - The abundance and properties of low-mass dark matter subhalos can be inferred by measuring the density and velocity structure of stellar streams, testing physical models of dark matter. Which streams make the most promising dark matter detectors, and which subhalos would they encounter? We use the semi-analytic model galacticus to simulate the Milky Way's dark subhalos, including tidal stripping under the influence of the galactic disk. Deriving stream initial conditions that best match present-day observations, we forecast subhalo encounters for 24 globular cluster streams around the Milky Way. Over their lifetimes, the 10 most perturbed streams are predicted to each experience ≈ 2-$12$ significant subhalo encounters with velocity kicks v_kick > 0.1 km s^−1. Jet, AAU, GD-1, and Palomar 5 lead the list, with Jet encountering twice the subhalos of any other stream. The subhalos that encounter streams have been tidally stripped to $1−20\%$ of their peak mass and are twice as compact as previous works have assumed. A spectroscopic survey of streams with sub-km s^−1 precision could reveal the influence of dark subhalos below the threshold of galaxy formation. Predicting the abundance and scatter of low-mass subhalos that reach the inner galaxy remains a dominant uncertainty in connecting stellar streams to models of dark matter.
ER -