2021/02/18 by Ramkishor Sharma
Physics and Astronomy · #astro-ph.CO
paper · pdf · doi:10.1103/physrevd.105.l041302
5 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:1912.12089
arxiv created 2021/02/18 · arxiv updated 2022/03/02
Generation of magnetic field during inflation can explain its presence over a wide range of scales in the Universe. In Ref.\citesharma2017, we proposed a model to generate these fields during inflation. These fields have nonzero anisotropic stress which lead to the generation of a stochastic background of gravitational waves (GW) in the early universe. Here we show that for a scenario of magnetogenesis where reheating takes place around QCD epoch, this stochastic GW background lies in the 95% confidence region of the GW signal probed by NANOGrav collaboration. This is the case when the generated electromagnetic field (EM) energy density is 3-10% of the background energy density at the end of reheating. For this case, the values of magnetic field strength B0 ∼ (3.8-6.9) × 10-11G and its coherence length ∼ 30 kpc at the present epoch. These values are for the models in which EM fields are of nonhelical nature. For the helical nature of the fields, these values are B0 ∼ (1.1-1.9) × 10-9G and its coherence length ∼ 0.8 Mpc.