On the radiative and thermodynamic properties of the cosmic radiations using Cobe Firas instrumental data: Sunyaev-Zeldovich distortion effect

TL;DR

This paper investigates the impact of the Sunyaev-Zel'dovich effect on the cosmic microwave background's thermodynamic properties using COBE FIRAS data, deriving analytical expressions for various radiative functions and new astrophysical parameters.

Contribution

It provides exact analytical expressions for thermodynamic functions of the Bose-Einstein spectrum affected by the SZ distortion, based on COBE FIRAS data and extends analysis over a wide redshift range.

Findings

Calculated thermodynamic functions at T=2.72548 K using COBE data

Derived expressions for entropy density and photon number density affected by mu-distortion

Compared results with standard CMB spectrum functions

Abstract

The Sunyaev-Zel'dovich effect is a small spectral distortion of the spectrum of the cosmic microwave background (CMB) radiation. This slight distortion is described by the Bose-Einstein (mu-type) distribution with non-zero chemical potential. It is now interesting to investigate the effect of this distortion on the integral characteristics of the Bose-Einstein spectrum. The thermal radiative and thermodynamic functions of the Bose-Einstein distribution are such integral characteristics. These functions are as follows: a) the total radiation power per unit area; b) total energy density; c) number density of photons; d) grand potential density; e) Helmholtz free energy density; f) entropy density; g) heat capacity at constant volume; h) enthalpy density; and i) pressure. The exact analytical expressions are obtained for the temperature dependences of these functions. Using experimental data measured by the COBE FIRAS instrument, the thermal radiative and thermodynamic functions are calculated at the monopole temperature T = 2.72548 K and at z = 0. A comparative analysis of the results obtained with the results for the same functions of the CMB spectrum is carried out. The thermal radiative and thermodynamic functions of the Bose-Einstein distribution are calculated in the redshift range from 10(5) to 3x10(6). The expressions are obtained for new astrophysical parameters, such as the entropy density/Boltzmann constant and number density, created by the mu- distortion of the CMB spectrum.