Reheating and particle creation in unimodular f(R, T) gravity

We study cosmological inflation and reheating in the unimodular f ( R , T ) gravity. During the reheating era, which takes place just after the end of inflation, the energy density of inflaton is converted to radiation energy through, for instance, rapid oscillation about the minimum of the potential. We quantify our investigation by calculating the reheating temperature. This quantity is written in terms of the spectral index and the power spectrum, which provides a suitable framework to constrain the parameter space of the model. We discuss the massless particle creation for a spatially flat, homogeneous and isotropic universe in the context of unimodular f ( R , T ) gravity. We obtain the number of created particles per unit volume of space. To avoid the complexity of solving the fourth order equations, we analyze the reheating in the Einstein frame by considering some specific illustrative examples and obtain the corresponding analytical solutions in addition to some numerical estimations.