Generation of strong magnetic fields via the small-scale dynamo during the formation of the first stars

TL;DR

This paper demonstrates through high-resolution simulations that turbulent small-scale dynamos can exponentially amplify magnetic fields during primordial star formation, likely affecting early stellar evolution.

Contribution

It shows that resolving the Jeans length with at least 30 grid cells is essential to capture dynamo activity in simulations of first star formation.

Findings

Magnetic fields are exponentially amplified during primordial star formation.

A minimum resolution of 30 grid cells per Jeans length is required to observe the dynamo.

Strong magnetic fields are generated early, potentially influencing star evolution.

Abstract

Here we summarize our recent results of high-resolution computer simulations on the turbulent amplification of weak magnetic seed fields showing that such fields will be exponentially amplified also during the gravitational collapse reminiscent to the situation during primordial star formation. The exponential magnetic field amplification is driven by the turbulent small-scale dynamo that can be only observed in computer simulations if the turbulent motions in the central core are sufficiently resolved. We find that the Jeans length, which determines the central core region, has to be resolved by at least 30 grid cells to capture the dynamo activity. We conclude from our studies that strong magnetic fields will be unavoidably created already during the formation of the first stars in the Universe, potentially influencing their evolution and mass distribution.