Cosmo-26

Dark sector models with a vanishing speed of sound

Not scheduled

20m

Gorlaeus gebouw (Leiden University)

Talk Dark Energy / Modified Gravity

Speaker

Darío Jaramillo-Garrido (Universidad Complutense de Madrid and IPARCOS-UCM)

Description

We develop a field theory description of the dark sector, constructed under the requirement of having a vanishing fluid sound speed so as not to spoil cosmic structure formation. The form of the field theory naturally arises in transverse diffeomorphism invariant scenarios, in which case the dark sector is unified into a single scalar field. After a systematic model selection, we classify the resulting families into adiabatic and non-adiabatic fluids. We find that, in general, the adiabatic families exactly reproduce the ΛCDM dark sector, while the non-adiabatic families admit the interpretation of an interacting dark matter and vacuum energy.