Ponente
Descripción
The cold dark matter (CDM) scenario has proved successful in cosmology.
However, we lack a fundamental understanding of its microscopic nature. Moreover, the
apparent disagreement between CDM predictions and subgalactic-structure observations
has prompted the debate about its behaviour at small scales. These problems could be
alleviated if the dark matter is composed of ultralight fields m ∼ 10 −22 eV, usually known
as fuzzy dark matter (FDM). Some specific models, with axion-like potentials, have been
thoroughly studied and are collectively referred to as ultralight axions (ULAs) or axion-like
particles (ALPs). In this work we consider anharmonic corrections to the mass term coming from a repulsive quartic self-interaction. Whenever this anharmonic term dominates, the field behaves as radiation instead of cold matter, modifying the time of matter-radiation equality. Additionally, even for high masses, i.e. masses that reproduce the cold mat-
ter behaviour, the presence of anharmonic terms introduce a cut-off in the matter power
spectrum through its contribution to the sound speed. We analyze the model and derive
constraints using a modified version of class and comparing with CMB and large-scale
structure data.
