Speaker
Description
Bosonic fields with very small masses, around $10^{-22}$ eV have been proposed as potential dark matter (DM) candidates. Unlike standard cold dark matter (CDM) particle models, ultra-light dark matter is more adequately described in terms of coherent fields on cosmological scales. In the scalar case, these models are known to suppress structure formation on sub-galactic scales, thus alleviating some of the claimed small-scale problems of the CDM scenario.
In this talk we explore the possibility of extending the ultra-light DM scenario to vector fields. We show that despite the presence of a coherent background vector field, the model can be compatible with the observed cosmological isotropy. We study the evolution of perturbations and compare with the scalar case. We find that in the so called wave regime, ultra-light vector DM generates a non-vanishing anisotropic stress which is the source of a gravitational wave background. We analyze the corresponding spectrum and compare with the sensitivity of present a future gravity wave detectors.
