Predicting the density profiles of the first halos

Understand

The first dark matter halos form by direct collapse from peaks in the matter density field, and evidence from numerical simulations and other analyses suggests that the dense inner regions of these objects largely persist today.

• These halos would be the densest dark matter structures in the Universe, and their abundance can probe processes that leave imprints on the primordial density field, such as inflation or an early matter-dominated era.
• They can also probe dark matter through its free-streaming scale.
• The first halos are qualitatively different from halos that form by hierarchical clustering, as evidenced by their $\rho\propto r^{-3/2}$ inner density profiles.