Star Stream Velocity Distributions in Cold Dark Matter and Warm Dark Matter Galactic Halos

Carlberg, Raymond G.; Jenkins, Adrian; Frenk, Carlos S.; Cooper, Andrew P.

Abstract

The dark matter subhalos orbiting in a galactic halo perturb the orbits of stars in thin stellar streams. Over time, the random velocities in the streams develop non-Gaussian wings. The rate of velocity increase is approximately a random walk at a rate proportional to the number of subhalos, primarily those in the mass range ≈106−7 M ⊙. The distribution of random velocities in long streams is measured in simulated Milky Way–like halos that develop in representative warm dark matter (WDM) and cold dark matter (CDM) cosmologies. The radial velocity distributions are well modeled as the sum of a Gaussian and an exponential. The resulting Markov Chain Monte Carlo fits find Gaussian cores of 1−2 km s−1 and exponential wings that increase from 3 km s−1 for 5.5 keV WDM, 4 km s−1 for 7 keV WDM, to 6 km s−1 for a CDM halo. The observational prospects to use stream measurements to constrain the nature of galactic dark matter are discussed.

Citation

Carlberg, R. G., Jenkins, A., Frenk, C. S., & Cooper, A. P. (2024). Star Stream Velocity Distributions in Cold Dark Matter and Warm Dark Matter Galactic Halos. The Astrophysical Journal, 975(1), Article 135. https://doi.org/10.3847/1538-4357/ad7b35

• Journal Article Type: Article
• Acceptance Date: Aug 15, 2024
• Online Publication Date: Oct 30, 2024
• Publication Date: Nov 1, 2024
• Deposit Date: Nov 8, 2024
• Publicly Available Date: Nov 8, 2024
• Journal: The Astrophysical Journal
• Electronic ISSN: 1538-4357
• Peer Reviewed: Peer Reviewed
• Volume: 975
• Issue: 1
• Article Number: 135
• DOI: https://doi.org/10.3847/1538-4357/ad7b35
• Keywords: Milky Way dark matter halo, Warm dark matter, Cold dark matter, Stellar streams
• Public URL: https://durham-repository.worktribe.com/output/3048017