Anisotropic inflation with a non-minimally coupled electromagnetic field to gravity

Adak M., Akarsu Ö., Dereli T., Sert O.

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, no.11, 2017 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2017
  • Doi Number: 10.1088/1475-7516/2017/11/026
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: inflation, modified gravity, cosmic magnetic fields theory, COSMOLOGICAL MODELS, UNIVERSE, FLATNESS, HORIZON
  • Istanbul Technical University Affiliated: Yes


We consider the non-minimal model of gravity in Y (R) F-2-form. We investigate a particular case of the model, for which the higher order derivatives are eliminated but the scalar curvature R is kept to be dynamical via the constraint YRFmn F-mn = -2/k(2) The ff ective fluid obtained can be represented by interacting electromagnetic field and vacuum depending on Y (R), namely, the energy density of the vacuum tracks R while energy density of the conventional electromagnetic field is dynamically scaled with the factor Y (R) 2. We give exact solutions for anisotropic inflation by assuming the volume scale factor of the Universe exhibits a power-law expansion. The directional scale factors do not necessarily exhibit power-law expansion, which would give rise to a constant expansion anisotropy, but expand nontrivially and give rise to a non-monotonically evolving expansion anisotropy that eventually converges to a non-zero constant. Relying on this fact, we discuss the anisotropic e-fold during the inflation by considering observed scale invariance in CMB and demanding the Universe to undergo the same amount of e-folds in all directions. We calculate the residual expansion anisotropy at the end of inflation, though as a result of non-monotonic behaviour of expansion anisotropy all the axes of the Universe undergo the same of amount of e-folds by the end of inflation. We also discuss the generation of the modified electromagnetic field during the first few e-folds of the inflation and its persistence against to the vacuum till end of inflation.