Fuzzy Aquarius: evolution of a Milky-way like system in the Fuzzy Dark Matter scenario

TL;DR

This paper presents a high-resolution simulation of a Milky Way-like galaxy in the Fuzzy Dark Matter framework, revealing core density profiles, velocity flattening, and complex structure evolution influenced by quantum effects.

Contribution

First high-resolution zoom-in simulation of a Milky Way-like halo in FDM, analyzing structure formation, core profiles, and evolution of collapsed structures over redshift.

Findings

Halo exhibits a cored density profile with several kpc core size.

Velocity profile shows flattening as a feature of FDM dynamics.

Structures do not reach solitonic ground state at formation but converge over time.

Abstract

We present the first high-resolution zoom-in simulation of a Milky-way-like halo extracted from the Aquarius Project in the Fuzzy Dark Matter (FDM) framework. We use the N-body code AX-GADGET, based on a particle oriented solution of the Schr\"{o}dinger-Poisson equations, able to detail the complexity of structure formation while keeping track of the quantum effects in FDM. The halo shows a cored density profile, with a core size of several kpc for a FDM mass of $m_{\chi}=2.5h \times 10^{-22}\ {\rm eV}/c^2$. A flattening is observed also in the velocity profile, representing a distinct feature of FDM dynamics. We provide a quantitative analysis of the impact of fuzziness on satellites in terms of abundance, mass, distance and velocity distribution functions and their evolution with redshift. Very interestingly, we show that all collapsed structures, despite showing a flat density profile at $z=0$, do not reach the solitonic ground-state at the time of formation: on the contrary, they asymptotically converge to it on a timescale that depends on their mass and formation history. This implies that current limits on FDM mass - obtained by applying simple scaling relations to observed galaxies - should be taken with extreme care, since single objects can significantly deviate from the expected asymptotic behavior during their evolution.