EFFECT OF BULK VISCOSITY TO THE LATE-TIME ACCELERATED EXPANSION IN f(Q, T) GRAVITY WITHIN THE FRAMEWORK OF OBSERVATIONAL DATASETS

TURKISH PHYSICAL SOCIETY 40TH INTERNATIONAL PHYSICS CONGRESS, Muğla, Türkiye, 2 - 06 Eylül 2024, ss.247

In this work, bulk viscous state has been investigated within the framework of f(Q, T)

scalar gravitational theory in the constraints of Pantheon+ SNeIa datasets. Field equations

shows that matter and energy content of the universe includes the bulk viscous state. We

have shown our modified gravity theory by choosing f(Q, T) = αQ + βT, where α and

β are free model parameters, Q is the non-metricity scalar and T is the trace of energy-

momentum tensor. Hubble parameter, energy density, deceleration parameter, effective

pressure and EoS parameters has been examined according to the redshift parameter for

understanding the cosmological properties of accelerated expansion. In this context, the

results shows the effect of the bulk viscous state to the late time acceleration of the

universe. We use the χ2 minimization together with the Markov Chain Monte Carlo

(MCMC) method for constraining our model according to the observational datasets.

Energy conditions of model has been obtained for checking the consistency of f(Q, T)

cosmological model. Null Energy Condition (NEC) and Dominant Energy Condition

(DEC) satisfy the positivity criteria. Violation of the Strong Energy Condition (SEC)

reveals the accelerating expansion behaviour. Results shows the similarity of f(Q, T)

gravity with Lambda Cold Dark Matter (ΛCDM) and quintessence and ghost models of

dark energy. In this context, bulk viscous f(Q, T) gravity model provide a convincing

description of the late time acceleration.

Keywords: f(Q, T) gravity, bulk viscosity, observational contraints