Modified f(Q)-gravity string cosmological models with observational constraints

Abstract

In the current study, we have investigated a modified $f\left(Q\right)$-gravity theory in an anisotropic, locally rotationally symmetric (LRS) Bianchi type-I spacetime universe model. The arbitrary function $f\left(Q\right)=Q+\Lambda$, where $\Lambda$ is the “cosmological constant,” and $Q$ is the non-metricity scalar, has been taken into consideration. To obtain the exact solution of the modified field equations, we considered a dusty string fluid matter source and the shear scalar ($\sigma$) is proportional to the expansion scalar ($\theta$). The resultant Hubble function has been fitted with observational datasets $H\left(z\right)$ and SNe Ia datasets of apparent magnitude $m\left(z\right)$ in order to obtain the best fit values for the cosmological parameters. And utilizing these best fit values throughout the investigation, the many cosmic phenomena are examined. We have investigated the cosmographic coefficients like $H,q,j,s$ to see if an accelerated dual mode expanding dark energy (DE) model of the universe exists. Our Om diagnostic study shows that our universe model is a quintessence example of a dark energy model. We have also calculated the universe’s present age.