Gas rich and gas poor structures through the stream velocity effect

Understand

Using adiabatic high-resolution numerical simulations we quantify the effect of the streaming motion of baryons with respect to dark matter at the time of recombination on structure formation and evolution.

• Formally a second order effect, the baryonic stream velocity has proven to have significant impact on dark matter halo abundance, as well as on the gas content and morphology of small galaxy clusters.
• In this work, we study the impact of stream velocity on the formation and gas content of haloes with masses up to $10^9 M_{\odot}$, an order of magnitude larger than previous studies.
• We find that the non-zero stream velocity has a sizable impact on the number density of haloes with masses $\lesssim$ few $\times 10^7 M_{\odot}$ up to $z=10$, the final redshift of our simulations.