Abstract Details
| Name: Ramkishor Sharma Affiliation: UNIVERSITY OF DELHI Conference ID: ASI2018_626 Title : A viable $f^2 F^{\mu\nu}F_{\mu\nu}$ model of inflationary magnetogenesis Authors and Co-Authors : Sandhya Jagannathan (University of Delhi) T. R. Seshadri (University of Delhi) Kandaswamy Subramanian (IUCAA) Abstract Type : Poster Abstract Category : General Relativity and Cosmology Abstract : Magnetic fields have been observed in galaxy, galaxy clusters and even in voids. A lower bound of strength $10^{-15}$ G on Mpc scales has been suggested by gamma ray observation of Blazars. However, the origin of these fields is still an open question. A lot of possible scenario has been suggested in the literature, f^2 F^{\mu\nu}F_{\mu\nu} type model (Ratra model) is one of them. Although the generated magnetic fields of this model satisfies the observed strength, they suffer from strong coupling and back-reaction problem. In our work, we have suggested a scenario that is free from these problems. In this scenario the coupling function, f grows during inflation and transits to a decaying phase post-inflation. By choosing a suitable evolution of coupling function, it has been demonstrated that the above-mentioned difficulties (arising from strong coupling and back-reaction) are avoided. However, to avoid back-reaction post inflation, reheating has to be below $ \approx 1.7 \times 10^4$ GeV. The generated magnetic energy spectrum is blue and it satisfies the gamma-ray bounds. |