The Dwarf Galaxy--Halo Connection from Milky Way Satellites

We present a forward-modeling framework to observationally infer the galaxy-halo connection in the dwarf galaxy regime. Our framework maps dark matter subhalo populations to four observable satellite properties —abundance, projected size, luminosity, and line-of-sight velocity dispersion — and statistically compares the resulting synthetic populations to observations. While previous analyses have typically relied on two or three observables, we jointly fit four, demonstrating that the dimensionality of the observable space matters as much as sample size. We use a sample of 21 Milky Way satellites, including classical dwarf spheroidals and ultra-faint dwarfs discovered within the SDSS footprint, and simultaneously infer the halo occupation fraction, the stellar mass-halo mass (SMHM) relation and its scatter, the velocity-mass relation, and the radial distribution of satellites. Key results include a shallow SMHM slope with large intrinsic scatter, consistent with stochastic star formation and reionization quenching at low halo masses, and a strong preference for an NFW satellite radial distribution. This framework is extensible to current surveys including DES and future surveys such as Rubin Observatory/LSST, and provides the empirical foundation for constraining dark matter models and early universe physics using the Milky Way satellite population.

Zoom: https://dipc-org.zoom.us/j/97883749268

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