RESUMEN
Fuzzy dark matter (FDM) made of ultralight bosonic particles is a viable alternative to cold dark matter with clearly distinguishable small-scale features in collapsed structures. On large scales, it behaves gravitationally like cold dark matter deviating only by a cutoff in the initial power spectrum and can be studied using N-body methods. In contrast, wave interference effects near the de Broglie scale result in new phenomena unique to FDM. Interfering modes in filaments and halos yield a stochastically oscillating granular structure which condenses into solitonic cores during halo formation. Investigating these highly nonlinear wave phenomena requires the spatially resolved numerical integration of the Schrödinger equation. In previous papers we introduced a hybrid zoom-in scheme that combines N-body methods to model the large-scale gravitational potential around and the mass accretion onto pre-selected halos with simulations of the Schrödinger-Poisson equation to capture wave-like effects inside these halos. In this work, we present a new, substantially improved reconstruction method for the wave function inside of previously collapsed structures. We demonstrate its capabilities with a deep zoom-in simulation of a well-studied sub-L_{*}-sized galactic halo from cosmological initial conditions. With a particle mass of m=2.5×10^{-22} eV and halo mass M_{vir}=1.7×10^{11} M_{â} in a (60 h^{-1} comoving Mpc)^{3} cosmological box, it reaches an effective resolution of 20 comoving pc. This pushes the values of m and M accessible to simulations significantly closer to those relevant for studying galaxy evolution in the allowed range of FDM masses.
RESUMEN
We study the gravitational collapse of axion dark matter fluctuations in the postinflationary scenario, so-called axion miniclusters, with N-body simulations. Largely confirming theoretical expectations, overdensities begin to collapse in the radiation-dominated epoch and form an early distribution of miniclusters with masses up to 10^{-12} M_{â}. After matter-radiation equality, ongoing mergers give rise to a steep power-law distribution of minicluster halo masses. The density profiles of well-resolved halos are Navarro-Frenk-White-like to good approximation. The fraction of axion dark matter in these bound structures is â¼0.75 at redshift z=100.
RESUMEN
The fuzzy dark matter (FDM) model treats DM as a bosonic field with an astrophysically large de Broglie wavelength. A striking feature of this model is O(1) fluctuations in the dark matter density on time scales which are shorter than the gravitational timescale. Including, for the first time, the effect of core oscillations, we demonstrate how such fluctuations lead to heating of star clusters and, thus, an increase in their size over time. From the survival of the old star cluster in Eridanus II, we infer m_{a}â³0.6â1×10^{-19} eV within modeling uncertainty if FDM is to compose all of the DM and derive constraints on the FDM fraction at lower masses. The subhalo mass function in the Milky Way implies m_{a}â³0.8×10^{-21} eV to successfully form Eridanus II. The region between 10^{-21} and 10^{-20} eV is affected by narrow band resonances. However, the limited applicability of the diffusion approximation means that some of this region may still be consistent with observations of Eridanus II.