Where to find a dark matter sterile neutrino?

Abstract

We propose a strategy of how to look for dark matter (DM) particles possessing a radiative decay channel and derive constraints on their parameters from observations of X-rays from our own Galaxy and its dwarf satellites. When applied to the sterile neutrinos in keV mass range, it allows a significant improvement of restrictions to its parameters, as compared with previous works.

Figures (2)

• Figure 1: Upper panel: Method used to obtain restrictions on DM decay in MW from blank sky XRB observations. The data is fitted by a power law (reduced $\chi^2 = 1.07$ for 82 d.o.f.) and XSPEC v11.3.2 is used to put a $3\sigma$ limit on the presence of DM line (via command "error <line norm> 9.0"). Lower Panel: Method used to obtain restrictions from LMC. Flux rapidly decreases for $E\gtrsim 2$ keV, most of the data points at higher energies are zero within statistical uncertainty. The solid green line is the sum of the total flux plus $3\sigma$ per energy bin. At $E\gtrsim 2$ keV the bound is dominated by errors and therefore can be improved significantly by increasing statistics.
• Figure 2: 3$\sigma$ restrictions on DM decay line from Milky way halo (XMM and HEAO-1 observations). Dashed line: total flux + $3\sigma$ restriction from LMC. Also shown the previous strongest limit from the clusters of galaxies Boyarsky:06b.