16 research outputs found
Phase Space Analysis and Thermodynamics of Interacting Umami Chaplygin gas in FRW Universe
In this work interacting Umami Chaplygin gas has been studied in flat FRW
model of universe in context of it's thermodynamic and dynamical behaviour. In
particular, considering Umami fluid as dark energy interacting with dark
matter, irreversible thermodynamics has been studied both for apparent and
event horizon as bounding horizon in two separate cases. Also the model has
been investigated in purview of dynamical systems analysis by converting the
cosmological evolution equations to an autonomous system of ordinary
differential equations. With some restrictions on model parameter and
coupling parameter , some cosmologically interesting critical points
describing late time accelerated evolution of the universe attracted by
cosmological constant and accelerated scaling attractor in quintessence era
have been found to alleviate coincidence problem.Comment: Accept 16 pages, 8 figure
Gravitationally induced matter creation and cosmological consequences
In this work, a two-fluid interacting model in a flat FLRW universe has been
studied considering particle creation mechanism with a particular form of
particle creation rate from different
aspects. Statistical analysis with a combined data set of SNe Ia (Supernovae
Type Ia) and Hubble data is performed to achieve the best-fit values of the
model parameters, and the model is compatible with current observational data.
We also perform a dynamical analysis of this model to get an overall
qualitative description of the cosmological evolution by converting the
governing equations into a system of ordinary differential equations
considering a proper transformation of variables. We find some non-isolated
sets of critical points, among which some usually are normally hyperbolic sets
of points that describe the present acceleration of the Universe dominated by
dark energy mimicking cosmological constant or phantom fluid. Scaling solutions
are also obtained from this analysis, and they can alleviate the coincidence
problem successfully. Finally, the thermodynamic analysis shows that the
Generalized second law of thermodynamics is valid in an irreversible
thermodynamic context.Comment: 26 pages, 14 captioned figure
Irreversible Thermodynamics of the Universe: Constraints from Planck
The present work deals with irreversible universal thermodynamics. The homogenous and isotropic flat model of the universe is chosen as open thermodynamical system and nonequilibrium thermodynamics comes into picture. For simplicity, entropy flow is considered only due to heat conduction. Further, due to Maxwell-Cattaneo modified Fourier law for nonequilibrium phenomenon, the temperature satisfies damped wave equation instead of heat conduction equation. Validity of generalized second law of thermodynamics (GSLT) has been investigated for universe bounded by apparent or event horizon with cosmic substratum as perfect fluid with constant or variable equation of state or interacting dark species. Finally, we have used three Planck data sets to constrain the thermal conductivity λ and the coupling parameter b2. These constraints must be satisfied in order for GSLT to hold for universe bounded by apparent or event horizons
Constraints from Planck Data
The present work deals with irreversible universal thermodynamics. The homogenous and isotropic flat model of the universe is chosen as open thermodynamical system and nonequilibrium thermodynamics comes into picture. For simplicity, entropy flow is considered only due to heat conduction. Further, due to Maxwell-Cattaneo modified Fourier law for nonequilibrium phenomenon, the temperature satisfies damped wave equation instead of heat conduction equation. Validity of generalized second law of thermodynamics (GSLT) has been investigated for universe bounded by apparent or event horizon with cosmic substratum as perfect fluid with constant or variable equation of state or interacting dark species. Finally, we have used three Planck data sets to constrain the thermal conductivity and the coupling parameter 2 . These constraints must be satisfied in order for GSLT to hold for universe bounded by apparent or event horizons
Phase Space Analysis and Thermodynamics of Interacting Umami Chaplygin Gas in FRW Universe
In this work interacting Umami Chaplygin gas has been studied in flat FRW model of universe in context of it’s thermodynamic and dynamical behaviour. In particular, considering Umami fluid as dark energy interacting with dark matter, irreversible thermodynamics has been studied both for apparent and event horizon as bounding horizon in two separate cases. Also the model has been investigated in purview of dynamical systems analysis by converting the cosmological evolution equations to an autonomous system of ordinary differential equations. With some restrictions on model parameter and coupling parameter , some cosmologically interesting critical points describing late time accelerated evolution of the universe attracted by cosmological constant and accelerated scaling attractor in quintessence era have been found to alleviate coincidence problem