The dark matter zooming past Earth isn't some smooth cloud; it’s a messy leftover scrap from ancient galaxy crashes.
March 30, 2026
Original Paper
Set the Night on FIRE: Building an Empirical Local Dark Matter Velocity Distribution
arXiv · 2603.25783
The Takeaway
For decades, scientists searching for dark matter assumed it was distributed evenly around us like a mist. New research shows it actually behaves like a swirling river of debris, carrying the 'skeletons' of smaller galaxies that the Milky Way swallowed billions of years ago.
From the abstract
The majority of terrestrial direct detection experiments for Dark Matter (DM) rely on the Standard Halo Model (SHM), which assumes the local DM velocity distribution follows a Maxwell-Boltzmann distribution. However, galaxy mergers can deposit DM that remains kinematically clustered today, inducing deviations from the smooth SHM prediction. Previous studies have suggested that the local stellar velocity distribution may serve as a tracer for DM populations originating from the same progenitor sy