Dissipative cosmology with $Λ$ from the first law of thermodynamics (2512.19911v1)

Abstract: We phenomenologically derive a cosmological model that includes both a cosmological constant term $Λ/3$ and a dissipative driving term $β(2 H^{2} + \dot{H})$ by applying the first law of thermodynamics to matter creation cosmology. Here $H$, $\dot{H}$, and $β$ are the Hubble parameter, the time derivative of $H$, and a non-negative dimensionless coefficient, respectively. The dissipative term is proportional to the Ricci scalar curvature, suggesting that the dynamic creation pressure has the same dependence. We examine the model's background evolution in the late universe and its horizon thermodynamics. The present model supports a transition from a decelerating universe to an accelerating universe when $β<0.5$. The second law of thermodynamics is always satisfied on the horizon, and maximization of entropy is satisfied in the final stage. We examine constraints on the present model using observed Hubble parameter data and the transitional and thermodynamic constraints and find that a weakly dissipative universe with $Λ$ is likely favored and consistent with our Universe. We also discuss irreversible entropy due to adiabatic particle creation, assuming a holographic-like matter creation cosmology.