Properties of Resonantly Produced Sterile Neutrino Dark Matter Subhalos

TL;DR

This study investigates the properties of subhalos in a universe with 7.1 keV sterile neutrino dark matter produced via the resonant Shi-Fuller mechanism, comparing results with thermal warm dark matter to understand small-scale structure effects.

Contribution

It provides the first detailed numerical analysis of subhalo properties for resonantly produced sterile neutrino dark matter, highlighting its consistency with observed Local Group structures.

Findings

Resonant sterile neutrino dark matter matches observed satellite distributions.

It alleviates the too-big-to-fail problem in galaxy formation.

Quantitative differences are identified between sterile neutrino and thermal warm dark matter models.

Abstract

The anomalous 3.55 keV X-ray line recently detected towards a number of massive dark matter objects may be interpreted as the radiative decays of 7.1 keV mass sterile neutrino dark matter. Depending on its parameters, the sterile neutrino can range from cold to warm dark matter with small-scale suppression that differs in form from commonly-adopted thermal warm dark matter. Here, we numerically investigate the subhalo properties for 7.1 keV sterile neutrino dark matter produced via the resonant Shi-Fuller mechanism. Using accurate matter power spectra, we run cosmological zoom-in simulations of a Milky Way-sized halo and explore the abundance of massive subhalos, their radial distributions, and their internal structure. We also simulate the halo with thermal 2.0 keV warm dark matter for comparison and discuss quantitative differences. We find that the resonantly produced sterile neutrino model for the 3.55 keV line provides a good description of structures in the Local Group, including the number of satellite dwarf galaxies and their radial distribution, and largely mitigates the too-big-to-fail problem. Future searches for satellite galaxies by deep surveys, such as the Dark Energy Survey, Large Synoptic Survey Telescope, and Wide Field Infrared Survey Telescope, will be a strong direct test of warm dark matter scenarios.