Narrow Results

In this paper, we reconstruct the late-time cosmological dynamics using a purely kinematic approach. In particular, considering a divergence-free parametrization for deceleration parameter $q$, we first derive the jerk parameter $j$ and then confront it with combination of various cosmological datasets. We use the most recent observational datasets consisting of the 1048 Pantheon Supernovae Ia data points in the redshift range $0.01<z<2.3$, the 51 data points of observational Hubble parameter (OHD) measurements in the redshift range $0.07\le z\le 2.36$, the Hubble constant $H_0$ (R19) and the CMB shift parameter measurements. We study the evolution of different cosmological quantities for the present model and compare it with the concordance $\mathrm{\Lambda }$CDM model. We find that only the combined Pantheon+OHD+R19 data shows good agreement with the $\mathrm{\Lambda }$CDM $(j=1)$ model within $1\sigma$ confidence region. We also find that our model successfully generates late time cosmic acceleration along with a decelerated expansion in the past.

In this paper, we delve into the cosmological assessments concerning the deceleration parameter $q=\kappa -\frac{\gamma }{H}$ in the context of the Bianchi type-III cosmological model within the framework of the Saez–Ballester theory of gravitation. By postulating a proportional relationship between the shear scalar ($\sigma$) and the expansion scalar ($\theta$), we derive solutions for the corresponding field equations. Additionally, we conduct an examination and evaluation of the model’s physical and kinematic parameters, including the jerk parameter and snap parameter, while also discussing the energy condition of the model. Through the depiction of graphical representations, we illustrate the variations of the cosmological parameters for specific sets of constants.

In this paper, we have proposed a model of accelerating universe with binary mixture of bulk viscous fluid and dark energy (DE) and probed the model parameters: present values of Hubble’s constant $H_0$, equation of state paper of DE ${\omega }_{\mathrm{\text{de}}}$ and density parameter of DE ${({\mathrm{\Omega }}_{\mathrm{\text{de}}})}_0$ with recent observational $H(z)$ data (OHD) as well as joint Pantheon compilation of SN Ia data and OHD. Using cosmic chronometric technique, we obtain $H_0=69.80\pm 1.64{\mathrm{\text{km s}}}^{-1}{\mathrm{\text{Mpc}}}^{-1}$ and $70.0258\pm 1.72{\mathrm{\text{km s}}}^{-1}{\mathrm{\text{Mpc}}}^{-1}$ by restricting our derived model with recent OHD and joint Pantheon compilation SN Ia data and OHD, respectively. The present age of the universe in derived model is estimated as $t_0=13.82\pm 0.33\mathrm{\text{Gyr}}$. Also, we observe that derived model represents a model of transitioning universe with transition redshift $z_t=0.7286$. We have constrained the present value of jerk parameter as $j_0=0.969\pm 0.0075$ with joint OHD and Pantheon data. From this analysis, we observed that the model of the universe, presented in this paper, shows a marginal departure from $\mathrm{\Lambda }$CDM model.

In this paper, we investigate the recently proposed New Barrow Agegraphic Dark Energy (NBADE) model by taking the distinct values of Barrow parameter $\mathrm{\Delta }$ in the context of Friedmann–Robertson–Walker (FRW) Universe. We have used different diagnostic tools to discriminate NBADE model from $\mathrm{\Lambda }$CDM model, namely statefinder pair $(r,s)$, $(r,q)$, ${\omega }_B-{\omega }_B^{\prime }$ pair, jerk parameter and $O_m(z)$ diagnostic planes. The trajectories for the evolution of statefinder parameters $r-s$, $r-q$, ${\omega }_B-{\omega }_B^{\prime }$ pair, jerk parameter and $O_m$ diagnostic are plotted of NBADE model using distinct values of the Barrow parameter $\mathrm{\Delta }$ at initially ${\mathrm{\Omega }}_{B0}=0.70$ and $H_0=67$.

In this study, a homogeneous and anisotropic Bianchi type-I universe model is considered taking the cosmological constant as a variable in the context of f (R, T) gravity. The presented model relies on a unique condition of constant jerk parameter as j = 1, which corresponds to a flat $\mathrm{\Lambda }$CDM model that leads to a variable deceleration parameter. The exact solution of the field equations is obtained under that condition, and the physical and geometrical features of the model are discussed through the paper. The model has been shown to be successful in explaining recent cosmological observations such as the universe’s expansion decelerates in the early universe and accelerates in the late universe, in agreement with their current data.