Testing CCDM Cosmology with the Radiation Temperature-Redshift Relation

TL;DR

This paper tests CCDM cosmology against the standard Lambda-CDM model using measurements of the radiation temperature-redshift relation, finding that current data cannot distinguish between the models but highlights potential for future thermal sector tests.

Contribution

It introduces a new parameter for CCDM cosmology related to photon production and constrains it using observational temperature-redshift data.

Findings

The photon production rate parameter is constrained to be near zero.

Lambda-CDM remains compatible with current temperature-redshift measurements.

Thermal sector tests could differentiate CCDM from Lambda-CDM in the future.

Abstract

The standard $\Lambda$CDM model can be mimicked at the background and perturbative levels (linear and non-linear) by a class of gravitationally induced particle production cosmology dubbed CCDM cosmology. However, the radiation component in the CCDM model follows a slightly different temperature-redshift $T(z)$-law which depends on an extra parameter, $\nu_r$, describing the subdominant photon production rate. Here we perform a statistical analysis based on a compilation of 36 recent measurements of $T(z)$ at low and intermediate redshifts. The likelihood of the production rate in CCDM cosmologies is constrained by $\nu_r = 0.024^{+0.026}_{-0.024}$ ($1\sigma$ confidence level), thereby showing that $\Lambda$CDM ($\nu_r=0$) is still compatible with the adopted data sample. Although being hardly differentiated in the dynamic sector (cosmic history and matter fluctuations), the so-called thermal sector (temperature law, abundances of thermal relics and CMB power spectrum) offers a clear possibility for crucial tests confronting $\Lambda$CDM and CCDM cosmologies.