The Milky Way’s Peculiar Primordial Halo: A Shallow Core with a Steep Decline
Li et al. (2025) use Gaia data and a numerical “reverse–compression” method to infer the Milky Way’s primordial dark matter halo. They find an unusual structure: a shallow inner core and a steep outer decline, unlike halos predicted by standard cold dark matter models. Neither baryonic feedback nor alternative dark matter models fully explains this combination, suggesting gaps in current theories of dark matter or galaxy formation.
How Many Starbursts Does It Take to Shape a Galaxy Core?
Olivia Mostow and collaborators explore how bursts of star formation reshape galaxy cores, addressing the core-cusp problem in low-mass galaxies. Using innovative simulations, they show that repeated bursts effectively flatten dark matter cusps, while single bursts struggle to do so, especially in ultra-faint dwarf galaxies. The study emphasizes the importance of burst timing and energy, offering insights into galaxy evolution and dark matter behavior.