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We examine the thermodynamic features of an exotic fluid known as modified cosmic Chaplygin gas in the context of homogeneous isotropic universe model. For this purpose, the behavior of physical parameters is discussed that help to analyze nature of the universe. Using specific heat formalism, the validity of third law of thermodynamics is checked. Furthermore, with the help of thermodynamic entities, the thermal equation of state is also discussed. The thermodynamic stability is explored by means of adiabatic, specific heat and isothermal conditions from classical thermodynamics. It is concluded that the considered fluid configuration is thermodynamically stable and expands adiabatically for an appropriate choice of parameters.

The discovery of accelerated expansion of the universe has unambiguously been proved by a diverse set of high-precision observational data accumulated from various astronomical sources [

Chaplygin gas is an intriguing model presented by a Russian physicist Chaplygin as a convenient soluble model to study the lifting force on the wing of an aeroplane in aerodynamics. It efficiently describes the cosmic expansion and elegantly discusses DM and DE in a unified form. The distinct feature of this model is its positive and bounded squared speed of sound

To discuss the cosmic history as well as get more accuracy with observational data, several modifications of CG have been presented which are obtained by introducing new parameters in its equation of state (EoS). Bento et al. [

Chaplygin gas models have stimulated many researchers to investigate their thermal stability. Santos et al. [

Here, we investigate thermodynamic stability of MCCG model in the background of isotropic and homogeneous universe model. In Section

In this section, we discuss the behavior of MCCG in the background of FRW universe model for different physical parameters and examine its stability through squared speed of sound. The line element for FRW universe model is given by

In the following, we use this equation to discuss different physical parameters.

The pressure of MCCG in terms of

Plots of

Here we discuss the effective EoS parameter of MCCG. Using (

For small volume

For large volume

The EoS parameter discusses both accelerated and decelerated phases of the universe and successfully describes the phase transitions (dubbed as flip) at a critical value

Figure

Plots of

The deceleration parameter is given by

Plots of

Here we analyze the stability of MCCG using speed of sound as

Plots of

In this section, we discuss thermodynamic stability of MCCG during its evolution. The stability conditions are given by the following [

The pressure reduces for both adiabatic as well as isothermal expansions as

Specific heat at constant volume

Differentiation of (

Plots of

To investigate the positivity of specific heat at constant volume, we consider specific heat in terms of temperature and entropy as

For a positive definite entropy, we assume

Plots of

Finally, we analyze the behavior of considered model through isothermal condition. For this purpose, we assume

In this paper, we have analyzed thermodynamic stability of MCCG within the framework of FRW universe model. We have examined the expanding evolution of the universe through different physical parameters like pressure, effective EoS, and deceleration parameters as well as speed of sound. The results of these parameters can be summarized as follows:

The consistent behavior of pressure with the evolutionary picture of the universe is obtained for the considered values of

The EoS parameter for MCCG depicts that decelerated and accelerated phases of our universe can be discussed for different values of parameter

The evolution of deceleration parameter against volume gives the decelerated universe when

We have analyzed the stability of MCCG through speed of sound and obtained stable regions at large volume for the considered values of

Finally, we have investigated thermodynamic stability of considered fluid configuration using adiabatic, isothermal, and specific heat conditions. We have found the validity of adiabatic as well as positivity of specific heat for the considered values of

No data were used to support this study.

The authors declare that they have no conflicts of interest.