On the Dwarf Galaxy Rotation Curve Diversity Problem

Abstract

In this paper, we show how baryonic physics can solve the problem of the striking diversity in dwarf galaxy rotation curves shapes. To this aim, we compare the distribution of galaxies of the SPARC sample, in the plane V2kpc-VRlast (V2kpc being the galaxy rotation velocity at 2 kpc, and VRlast being the outermost one), with that of galaxies that we simulated, taking account of baryonic effects. The scatter in the rotation curves in the V2kpc-VRlast plane, as well as the trend of the SPARC sample, and our simulated galaxy distribution is in good agreement. The solution of the “diversity” problem lies in the ability of the baryonic process to produce non-self-similar haloes, contrary to DM-only simulations. We show also that baryonic effects can reproduce the rotation curves of galaxies such as IC2574, which are characterized by a slow rise in radius. A solution to the diversity problem can be obtained taking the baryon physics effects appropriately into account.

Keywords

• cosmology
• dark matter
• small-scale problems of the ΛCDM model