Observational viability of fractional holographic dark energy in LRS Bianchi type-I cosmological model

Abstract

We scrutinized the Locally Rotational Symmetry (LRS) Bianchi type-I cosmological model in the presence of fractional holographic dark energy. We calculate the value of the Hubble parameter $H(z)$ using the field equations. After that, we fit the model by employing the MCMC techniques to observational data, which includes Hubble, Hubble+BAO, Hubble+Pantheon+Shoes, and Hubble+BAO+Pantheon+Shoes datasets. With the help of these datasets, we calculate the model parameters, viz. $H_{0}(z), \alpha,$ and $\Omega_{m_{0}}$. The value of $H_{0}(z),\alpha$ and $\Omega_{m_{0}}$ lies in the range $67.688^{+1.246}_{-1.197}- 67.80^{+1.23}_{-1.23}, 0.86^{+0.14}_{-0.15}- 0.885^{+0141}_{-0.149}$ and $0.264^{+0.018}_{-0.018}- 0.27^{+0.02}_{-0.02}$ respectively. Our results indicate that the evolution of the density parameters corresponding to dark energy (DE) and dark matter (DM), particularly for $\alpha=1.01$, along with the transition at $z_{t} = 0.55$ of the deceleration parameter $q$ from positive values to $-1$, reflects a phase of accelerated expansion that closely resembles the $\Lambda$CDM model. The behavior of the equation of state (EoS) parameter further demonstrates that the Universe's evolution aligns well with the framework of the fractional holographic dark energy (FHDE) model, suggesting its compatibility with scenarios of late-time cosmology. Moreover, the analysis of the statefinder diagnostics ${(r,s)}$ and the present value of ${(r,s)} = (0.74,0.07)$ reveal characteristics that converge towards the $\Lambda$CDM fixed point. A comparison between the observational constraints on our model parameters and those of the $\Lambda$CDM model exhibits a strong degree of agreement, thereby reinforcing the physical plausibility and consistency of the proposed cosmological model.