Speaker
Description
Dark matter at the keV scale has become an active topic in the last decade. The NuSTAR x-ray observatory, with its energy bandpass 3--150 keV and wide-angle aperture for unfocused x-rays, is an ideal platform to search for decaying keV-scale dark matter, e.g. sterile neutrinos. Previous NuSTAR analyses constrained much of the sterile-neutrino parameter space for masses ~10--40 keV, improving upon previous instruments by nearly an order of magnitude, but were generally limited at lower masses by the irreducible instrument background. After reviewing our group's previous NuSTAR analyses, I will describe our recent efforts to apply novel background-rejection and modeling techniques to long-exposure spectra of the Milky Way halo, further constraining the parameter space for 6--40 keV sterile neutrinos. These improvements will allow NuSTAR to begin to test some of the models of the 3.5-keV anomaly.
