DR. SHARANYA SUR

Over the course of the last decade, a great deal of progress has been made in understanding the physical processes governing the birth of the First stars and their influence on later epochs of structure formation. These studies have ignored the possible role of magnetic fields primarily, because the field strengths predicted from either cosmological processes or astrophysical mechanisms are weak or have large uncertainties. However, recent cosmological simulations have revealed that the self-gravitating regions in which First stars form contain significant turbulent motions. This has strong implications on the subsequent evolution, in particular on the generation of magnetic fields via Small-scale dynamo action. In this contribution, we show using high-resolution numerical simulations, that in the presence of turbulence, initial weak seed magnetic fields are exponentially amplified by the small-scale dynamo during the formation of the First stars. Our numerical experiment shows that the field amplification due to the dynamo provides additional amplification over what is expected from pure gravitational compression of the field lines. We find that the presence of the small-scale dynamo can only be identified in numerical simulations where the turbulent motions in the central collapsing core are resolved by at least 32 grid cells. We conclude that turbulent amplification of magnetic fields is a possible agent for magnetic field generation during the birth of the First stars and discuss implications for the subsequent cosmic evolution.