2020/02/04 by Archana Sangwan, S. Shankaranarayanan, Sangwan, Archana +1
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geomagnetism and Paleomagnetism Studies #Geophysics and Gravity Measurements #Solar and Space Plasma Dynamics
paper · pdf · doi:10.48550/arxiv.2002.01272
openalex publication_date 2020/02/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The origin of large-scale magnetic fields in the Universe is still unknown. Observations suggest the presence of nGauss primordial magnetic fields at the last scattering surface. The presence of such fields will affect the evolution of cosmological perturbations and potentially leave an imprint on the CMB anisotropies. Here, we show that the B-mode power spectrum carries a clear signature of the stochastic primordial magnetic fields up to a few nGauss. Specifically, the presence of nGauss primordial magnetic fields changes the BB power spectrum at all scales. At large scales, the tensor modes contribute to the B-mode spectrum, while non-vanishing vector modes contribute at small scales. We show that the B-mode of CMB carry a distinct signature of the primordial magnetic fields. To validate our prediction, we use BICEP2 and POLARBEAR data and find that B-mode observations from the experiments are consistent with non-zero primordial fields. We also use the BICEP2 observations to constrain the primordial magnetic field. We provide a detailed analysis of the B-mode polarization of the CMB with primordial magnetic fields and investigate the implications for the upcoming CMB missions.