The imprint of the relative velocity between baryons and dark matter on the 21-cm signal from reionization

Understand

The post-recombination streaming of baryons through dark matter keeps baryons out of low mass (<10^6 solar masses) halos coherently on scales of a few comoving Mpc.

• It has been argued that this will have a large impact on the 21-cm signal before and after reionization, as it raises the minimum mass required to form ionizing sources.
• Using a semi-numerical code, we show that the impact of the baryon streaming effect on the 21-cm signal during reionization (redshifts z approximately 7-20) depends strongly on the cooling scenario assumed for star formation, and the corresponding virial temperature or mass at which stars form.
• For the canonical case of atomic hydrogen cooling at 10^4 Kelvin, the minimum mass for star formation is well above the mass of halos that are affected by the baryon streaming and there are no major changes to existing predictions.