Institute for Advanced Study Astrophysics Seminar

Ultralight axions have gained great relevance in modern cosmology, becoming a promising candidate to describe the dark matter of the Universe. Axion models in which the scalar field potential includes only the quadratic term, usually referred as the free case, have been extensively studied in the literature. A distinctive signature of these models, with respect to the standard cold dark matter, is the presence of a cut-off in the mass power spectrum and the prediction of cored density dark matter halos. However, such models do not capture all the implications that arise when including a full axion potential. In this talk, I will discuss some results of studies of the cosmological evolution of linear perturbations, and its comparison to the cold dark matter and the free case, which reveals an enhancement in the amplitude of the mass power spectrum just before the cut-off scale, due to the non–linearity of the axion–like potential. As well, I will discuss current and future observational constraints that could help us assess the importance of self-interactions.