Leibniz MMS Days 2020 - Abstract

Berlok, Thomas

The impact of magnetic fields on cold streams feeding galaxies

High redshift, massive halos are observed to have sustained, high star formation rates which require that the amount of cold gas in the halo is continuously replenished. The cooling time scale for the hot virialized halo gas is too long to provide the source of cold gas. Supersonic, cold streams have been invoked as a mechanism for feeding massive halos at high redshift and deliver the cold gas required for continued star formation at the rates observed. The cold streams are likely to be subject to the supersonic version of the Kelvin-Helmholtz instability (KHI) which eventually leads to stream disruption. In this talk I present an idealized model of magnetized cold streams and show that magnetic fields can allow streams to survive ∼ 2 − 8 times longer and, consequently, that streams ∼ 2 − 8 times thinner can reach the central galaxy if the magnetic field strength is ∼ 0.3 − 0.8μG.