Cosmological constrains on fast transition Unified Dark Matter models

Ruth Lazkoz,Iker Leanizbarrutia,Vincenzo Salzano

doi:10.1088/1742-6596/600/1/012028

Abstract

In this work we show the results obtained applying a Unified Dark Matter (UDM) model with a fast transition to a set of cosmological data. Two different functions to model the transition are tested, and the feasibility of both models is explored using CMB shift data from Planck [1], Galaxy Clustering data from [2] and [3], and Union2.1 SNe Ia[4]. These new models are also statistically compared with the ACDM and quiessencemodels using Bayes factor through evidence. Bayesian inference does not discard the UDM models in favor of ACDM.

Highlights

In Unified Dark Matter (UDM) models the role of the dark energy and dark matter are played by a single fluid
Fast transition UDM models with scalar fields are compatible with observational data [9]
The Galaxy Clustering (GC) data we use are the measurements of H(z)rs(zd)/c and DA(z)/rs(zd) from the two dimensional two-point correlation function measured at z = 0.35 by [2] using a SDSS DR7 Luminous Red Galaxies sample, and at z = 0.57 by [3] using the CMASS galaxy sample from BOSS

Summary

Introduction

In Unified Dark Matter (UDM) models the role of the dark energy and dark matter are played by a single fluid. Among the different UDM models, the ones with fast transitions are very interesting. In principle these models can be clearly distinguished from a standard ΛCDM without being ruled out by observational data. Whereas this is not the case for the generalized Chaplygin gas [7]. UDM models with fast transitions can provide an alternative explanation of the accelerated expansion of the universe [8], as they can fit the experimental data quite well, while they provide interesting and different new features.

UDM Models

GC data

SNe Ia data

Discussion