Related papers: Three thermodynamically-based parametrizations of …
We use type Ia supernovae (SN Ia) data in combination with recent baryonic acoustic oscillations (BAO) and cosmic microwave background (CMB) observations to constrain a kink-like parametrization of the deceleration parameter ($q$). This…
We revisit the epoch of cosmic speed-up characterized by the redshift of transition from a decelerated to an accelerated phase. This redshift is termed the transition redshift ($z_t$). We use the spatially Flat and Non-Flat variants of the…
The new 182 gold supernova Ia data, the baryon acoustic oscillation measurement and the shift parameter determined from the Sloan Digital Sky Survey and the three-year Wilkinson Microwave Anisotropy Probe data are combined to reconstruct…
We investigate variational problems in quantum thermodynamics at positive temperature, in which admissible states are constrained by prescribed outcomes of a finite set of measurements. We solve a problem raised by the recent work [Liu,…
A particular kind of quintessence is considered, with equation of motion $p_Q/\rho_Q = -1$, corresponding to a cosmological term with time-dependence $\Lambda(t) = \Lambda(t_0) (R(t_0)/R(t))^{P}$ which we examine initially for $0 \leq P <…
In this paper, 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 are discussed that…
Many ambitious experiments have been proposed to constrain dark energy and detect its evolution. At present, observational constraints are consistent with a cosmological constant and there is no firm evidence for any evolution in the dark…
Bulk dark energy properties are determined by the redshift evolution of its pressure-to-density ratio, $w_{de}(z)$. An experimental goal is to decide if the dark energy is dynamical, as in the quintessence (and phantom) models treated here.…
The Barboza-Alcaniz EoS parametrization has been considered and its $q$-parametrization has been investigated in search for a thermodynamic motivation. For this, we have studied the validity of the generalized second law of thermodynamics…
We explore recent estimations of the Hubble parameter $H$ depending on redshift $z$, which include 31 $H(z)$ data points measured from differential ages of galaxies and 26 data points, obtained with other methods. We describe these data…
Cosmic acceleration may be due to modified gravity, with effective field theory or property functions describing the theory. Connection to cosmological observations through practical parametrization of these functions is difficult and also…
There has been recent interest in the cosmological consequences of energy-momentum-powered gravity models, in which the matter side of Einstein's equations includes a term proportional to some power, $n$, of the energy-momentum tensor, in…
We numerically study the dynamics after a parameter quench in the one-dimensional transverse-field Ising model with long-range interactions ($\propto 1/r^\alpha$ with distance $r$), for finite chains and also directly in the thermodynamic…
We study cosmological models involving a single real scalar field that has an equation of state parameter which evolves with cosmic time. We highlight some common parametrizations for the equation of state as a function of redshift in the…
Time-varying dark energy is often modeled in observational analyses through generic parameterizations of its equation of state $w(z)$, which typically use two free parameters $\{w_0, w_a\}$ to span a broad range of behaviors as a function…
In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…
We introduce two new diagnostics of dark energy (DE). The first, Om, is a combination of the Hubble parameter and the cosmological redshift and provides a "null test" of dark energy being a cosmological constant. Namely, if the value of…
We study the evolution of the cosmological parameters, namely, the deceleration parameter $q(z)$ and the parameter of effective equation of state in a universe contains, besides the ordinary matter and dark energy, a self-interacting…
The expansion rate of the Universe changes with time, initially slowing (decelerating) when the universe was matter dominated, because of the mutual gravitational attraction of all the matter in it, and more recently speeding up…
We investigate the thermodynamic and phenomenological implications of a cosmological model governed by fractional entropy applied to the apparent horizon of a flat Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) universe. By utilizing the…