Formation and structure of ultralight bosonic dark matter halos

TL;DR

This paper uses cosmological simulations to study ultralight bosonic dark matter halos, revealing solitonic cores with oscillations and confirming the core-halo mass relation, while showing halo properties align with collisionless models.

Contribution

It provides detailed simulation-based insights into the formation, structure, and dynamics of ultralight bosonic dark matter halos, confirming key theoretical relations.

Findings

Solitonic cores form with strong oscillations.

Core-halo mass relation is confirmed.

Halo properties match collisionless simulations on large scales.

Abstract

We simulate the formation and evolution of ultralight bosonic dark matter halos from cosmological initial conditions. Using zoom-in techniques we are able to resolve the detailed interior structure of the halos. We observe the formation of solitonic cores and confirm the core-halo mass relation previously found by Schive et al. The cores exhibit strong quasi-normal oscillations that remain largely undamped on evolutionary timescales. On the other hand, no conclusive growth of the core mass by condensation or relaxation can be detected. In the incoherent halo surrounding the cores, the scalar field density profiles and velocity distributions show no significant deviation from collisionless N-body simulations on scales larger than the coherence length. Our results are consistent with the core properties being determined mainly by the coherence length at the time of virialization, whereas the Schr\"odinger-Vlasov correspondence explains the halo properties when averaged on scales greater than the coherence length.