2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/195499We 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improvement of restrictions to its parameters, as compared with previous works.5 pp, revtex; v3: 1-sigma limits have been replaced by more conservative 3-sigma limits, a picture illustrating the data analysis methods has been adedAstrophysicstext