Testing dark matter warmness and quantity via the reduced relativistic gas model

TL;DR

This paper employs the reduced relativistic gas model to constrain dark matter and dark energy parameters, considering warm dark matter effects, and finds that the standard Lambda Cold Dark Matter model remains most favored, though alternatives with minimal dark matter are viable.

Contribution

It introduces the use of the reduced relativistic gas model to efficiently explore bounds on dark matter and dark energy, including warm dark matter effects, using multiple cosmological tests.

Findings

Lambda CDM is the most favored model based on combined data.

A model with very small dark matter quantity is viable according to 2dfGRS data.

The RRG model effectively explores parameter space with computational efficiency.

Abstract

We use the framework of a recently proposed model of reduced relativistic gas (RRG) to obtain the bounds for $\Omega$'s of Dark Matter and Dark Energy (in the present case, a cosmological constant), taking into consideration an arbitrary warmness of Dark Matter. An equivalent equation of state has been used by Sakharov to predict the oscillations in the matter power spectrum. Two kind of tests are accounted for in what follows, namely the ones coming from the dynamics of the conformal factor of the homogeneous and isotropic metric and also the ones based on linear cosmic perturbations. The RRG model demonstrated its high effectiveness, permitting to explore a large volume in the space of mentioned parameters in a rather economic way. Taking together the results of such tests as Supernova type Ia (Union2 sample), $H(z)$, CMB ($R$ factor), BAO and LSS (2dfGRS data), we confirm that $\La$CDM is the most favored model. At the same time, for the 2dfGRS data alone we found that an alternative model with a very small quantity of a Dark Matter is also viable. This output is potentially relevant in view of the fact that the LSS is the only test which can not be affected by the possible quantum contributions to the low-energy gravitational action.