Gravitational potential evolution in Unified Dark Matter Scalar Field Cosmologies: an analytical approach

TL;DR

This paper analytically studies the evolution of gravitational potential in non-adiabatic Unified Dark Matter scalar field models, providing an accurate approximation useful for future cosmological analyses.

Contribution

It introduces an analytical approximation for the gravitational potential in a specific class of Unified Dark Matter models with scalar fields, matching background evolution with LambdaCDM.

Findings

Provides a Bessel function approximation for Phi after recombination

Models predict the same background as LambdaCDM but with non-zero sound speed

Facilitates future detailed analysis of scalar field dark matter models

Abstract

We investigate the time evolution of the gravitational potential Phi for a special class of non-adiabatic Unified Dark matter Models described by scalar field lagrangians. These models predict the same background evolution as in the LambdaCDM and possess a non-vanishing speed of sound. We provide a very accurate approximation of Phi, valid after the recombination epoch, in the form of a Bessel function of the first kind. This approximation may be useful for a future deeper analysis of Unified Dark Matter scalar field models.