Vipin Chandra Dubey

In this paper, we examine a cosmological model with a new parametrization of the dark energy equation of state using a single parameter, [ ], to measure departures from the typical [ ]CDM case. The growth rate of cosmic structure and the statefinder hierarchy is used as diagnostics to analyze the model. A [ ] analysis is also performed, in which [ ] represents the dark energy equation of state parameter and the prime signifies differentiation with regard to [ ], where [ ] is the scale factor. We also investigate the evolution of the apparent magnitude and the Hubble parameter, contrasting the model’s predictions with those of [ ]CDM and with observable data from Type Ia Supernovae and Hubble parameter observations. We find that the cosmos accelerates after decelerating in the recent cosmic past, but does not asymptotically approach a de Sitter phase in the far future as does the classic [ ]CDM model. Rather, a second transition — from acceleration to deceleration — is what the model anticipates. Last, as a diagnostic of the model’s behavior under minor perturbations, we evaluate the squared sound speed to determine the dynamical stability of the model.

Our work focuses on the late-time constraints of dynamical Chern–Simons modified gravity (CSMG) theory in the Friedmann–Lemaître–Robertson–Walker (FLRW) universe. We determine which possibilities are physically plausible by examining how well the model fits the data. We challenge the cosmological model using the most current observational evidence, specifically the Supernovae type Ia (SN Ia), Observational Hubble data (OHD), Baryonic acoustic oscillations (BAO) and cosmic microwave background (CMB) observations. The [ ]-minimization technique is used to constrain the model parameters. In addition, we pick our model using the Bayesian Information Criterion (BIC) and the Akaike Information Criterion (AIC), and we compare it to the [ ]CDM model, which is our reference. The evolution of the effective equation of state (EoS) parameter, deceleration parameter (DP), and cosmographic parameters (CP) is thoroughly explored using the model parameters’ best fit values. These observational data sets indicate a strong agreement between the theoretical model and the observations. The dynamical behavior of DP explains the shift for the CSMG Universe from a decelerated to an accelerated expanding phase. In the distant future, the universe will approach the [ ] cold dark matter ([ ]CDM) model in terms of best fit values for model parameters.

This study is dedicated to the dynamic exploration of Barrow holographic dark energy (BHDE) inflation within the Granda–Oliveros (GO) cut-off framework. The investigation employs the Friedmann–Lemaître–Robertson–Walker (FLRW) cosmological model and takes place within the context of the Chern–Simons (CS) model of modified gravity (MG) theory. The aim of this analysis is to apply Hubble parameter and observational data from the Pantheon sample of Supernovae (SNIa) in conjunction with the most recent cosmic chronometer dataset to derive constraints on the BHDE scenario. We employ Markov chain Monte Carlo (MCMC) analysis to utilize the most recent cosmological data to constrain its parameters. Thus, we use the dark energy density parameter, deceleration parameter (DP) and equation of state (EoS) parameter to study cosmic evolution. The transition from decelerated to accelerated expanding phase for the BHDE universe is explained through dynamical behavior of DP. The evolutionary trajectories of [ ] plain are examined. Additionally, we use the Bayesian information criterion (BIC) and the Akaike information criterion (AIC) for model selection, and we compare our model to the [ ]CDM model, which serves as our reference.

We investigate Kaniadakis holographic dark energy (KHDE) model taking the apparent horizon as the IR cutoff in a flat Friedmann-Lemaître-Robertson-Walker (FLRW) universe. We apply variant dark energy (DE) diagnostic tool to study KHDE model in flat universe with different values of the constant [ ] and Kaniadakis entropy parameter [ ]. We use the tools statefinder hierarchy [ ], fractional growth parameter [ ] and composite null diagnostic (CND), which is blend of [ ] and [ ]. The evolution of trajectories of [ ] and [ ] depicts that there occur degeneracies in early time and also in the far future, whereas, in between these two extremes they are discriminated distinctly. The analysis of the present work shows that by the inclusion of fractional growth parameter [ ] with statefinder hierarchy (CND) degeneracy is removed reasonably, particularly more in the low redshift region.

In this paper, we investigate the recently proposed New Barrow Agegraphic Dark Energy (NBADE) model by taking the distinct values of Barrow parameter [ ] in the context of Friedmann–Robertson–Walker (FRW) Universe. We have used different diagnostic tools to discriminate NBADE model from [ ]CDM model, namely statefinder pair [ ], [ ], [ ] pair, jerk parameter and [ ] diagnostic planes. The trajectories for the evolution of statefinder parameters [ ], [ ], [ ] pair, jerk parameter and [ ] diagnostic are plotted of NBADE model using distinct values of the Barrow parameter [ ] at initially [ ] and [ ].