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arXiv · 2405.18522

Star Stream Velocity Distributions in CDM and WDM Galactic Halos

Raymond G. Carlberg·Adrian Jenkins·Carlos S. Frenk·Andrew P. Cooper
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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 $\approx 10^{6-7} M_\odot$. The distribution of random velocities in long, thin, streams is measured in simulated Milky Way-like halos that develop in representative WDM and CDM cosmologies. The radial velocity distributions are well modeled as the sum of a Gaussian and an exponential. The resulting MCMC fits find Gaussian cores of 1-2 km/sec and exponential wings that increase from 3 km/sec for 5.5 keV WDM, 4 km/sec for 7 keV WDM, to 6 km/sec for a CDM halo. The observational prospects to use stream measurements to constrain the nature of galactic dark matter are discussed.

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Raymond G. Carlberg, Adrian Jenkins, Carlos S. Frenk, Andrew P. Cooper. 2024-08-16. Star Stream Velocity Distributions in CDM and WDM Galactic Halos. https://arxiv.org/abs/2405.18522

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