Inflationary cosmology- A new approach using Non-linear electrodynamics

Abstract

We explore a new kind of NLED field as a source of gravity, which can accelerate the Universe during the inflationary era. We propose a new type of NLED lagrangian which is characterised by two parameters: α (dimensionless parameter) and β (dimensionful parameter). We investigate the classical stability and the causality aspects of this model of inflationary expansion by demanding that the speed of the sound wave and . Corresponding to , we find for α = 0.1(1.0). The equation of state parameter ω = −1/3 requires corresponding to . We find that the Universe is accelerating i.e. (which results in the deceleration parameter q < 0 (i.e. ω > −1/3)), provided . During inflation, the energy density is found to be maximum and is given by . The magnetic field necessary to trigger the inflation is found to be , where is the energy density of the Universe during the inflationary expansion. Our model also predicts the e-fold number that the magnetic field at the end of inflation is about B = 10−10 (10−4) Gauss corresponding to z = 0(1000) and this agrees quite well with the experimental prediction of the e-fold number. With α = 0.3(1.0) and , we find the scalar spectral index n s = 0.9649, consistent with the PLANCK 2018 CMB data. Further, with , we predicts the tensor-to-scalar ratio r = 0.1417(0.1449) and the tensorial spectral index .