Small-scale structure in vector dark matter

We investigate the differences in the small-scale structure of vector dark matter (VDM) and scalar dark matter (SDM) using 3+1 dimensional simulations of single/multicomponent Schrodinger-Poisson system. We find that the amount of wave interference, core-to-halo mass ratio (and its scatter), spin of the core, as well as the shape of the central regions of dark matter halos can distinguish VDM and SDM. Starting with a collection of idealized halos (self-gravitating solitons) as an initial condition, we show that the system dynamically evolves to an approximately spherically symmetric configuration that has a core surrounded by a halo of interference patterns in the mass density. In the vector case, the central soliton in less dense and has a smoother transition to an r(-3) tail compared to the scalar case. As compared to SDM, wave interference in VDM is similar to 1/root 3 times smaller, resulting in fewer low and high density regions, and more diffuse granules in the halo. The ratio of VDM core mass to the total halo mass is lower than that in SDM, with a steeper dependence on the total energy of the system and a slightly larger scatter. Finally, we also initiate a study of the evolution of intrinsic spin angular momentum in the VDM case. We see a positive correlation between the total intrinsic spin in the simulation and the spin of the final central core, with significant scatter. We see large intrinsic spin in the core being possible even with vanishing amounts total angular momentum in the initial conditions (at least instantaneously). Our results point towards the possibility of distinguishing VDM from SDM using astrophysical and terrestrial observations.

Automated summary

By simulating the small-scale structure of vector dark matter (VDM) and scalar dark matter (SDM), we found that the amount of wave interference, core-to-halo mass ratio, spin of the core, and shape of the central regions of dark matter halos can distinguish VDM and SDM. VDM has less wave interference, lower core-to-halo mass ratio, smoother transition of the central soliton, and more diffuse granules in the halo compared to SDM. This research is significant for distinguishing dark matter types through astrophysical and terrestrial observations.