Primordial Magnetic Fields through Large Scale Structure

Salome Mchedlidze (Göttingen)
Friday, March 4, 2022 - 12:00pm to 1:00pm

Magnetic fields are ubiquitous on all cosmic scales probed so far, from planets and stars to large scale, coherent (up to kpc scales and with the strengths of microGauss) fields found in galaxies and galaxy clusters. The origin of these fields still remains unknown. A leading possible explanation is that the observed fields are amplified remnants of significantly weaker, primordial seed magnetic fields generated in the early Universe. An intriguing possibility of having very weak magnetic fields in cosmic voids, as hinted at by observations of distant blazars, is strengthening the view of the relic magnetisation of the Universe. The major questions in the studies of primordial magnetic fields (PMFs) include: what are the generation scenarios of primordial seed fields and how do they evolve in the early Universe and later, during structure formation? In our work, we study inflation-generated PMFs which might have unlimited correlation length scales and causally, phase-transition generated fields with correlation lengths limited by the Hubble length scale (at the moment of generation). We use the cosmological magnetohydrodynamical (MHD) code ENZO to evolve these PMFs during large scale structure formation. For the first time, we account for the magnetic field dynamics prior to recombination. In this talk, I will discuss the evolution of PMFs from the early Universe till the current epoch. I will present our findings which include the distinctive evolution of different seed fields retaining the information of magnetic initial conditions on the largest scales of the Universe. Finally, I will talk about the observational perspective of distinguishing between different primordial magnetogenesis scenarios.

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