کوروش نوذری

Reheating is a process by which the inflaton’s energy density transfers to conventional matter after cosmic inflation. Currently, there is no cosmic observational evidence to directly detect the reheating era, but it may impose additional constraints on inflationary models. Depending upon the model, e-folding number during reheating Nre and the final reheating temperature Tre, as well as its effective equation of state parameter ωre, may be directly linked to the inflation observables such as the scalar spectral index ns and the tensor-to-scalar ratio r. By restricting the values of the effective equation of state parameter observationally, one can derive more stringent limits on inflationary models than those obtained from other routes. In this paper, we are interested to consider the reheating era in an inflation model with a nonminimal derivative coupling of the scalar field to impose some severe constraints on the parameter space of the model in the light of Planck 2018 data. We study the reheating final temperature and e-folds number in terms of the scalar spectral index and ωre within a numerical analysis on the model’s parameter space. To realize a viable range of the reheating equation of state parameter in this nonminimal derivative inflation model, we obtain some observationally acceptable subspaces in the Nre − ωre phase plane.