Sterile neutrinos as subdominant warm dark matter – Dan Cumberbatch

Date: Tue. November 13th, 2007, 11:30 am-12:30 pm
Location: Rockefeller 221

In light of recent findings which seem to disfavor a scenario with (warm) dark matter entirely constituted of sterile neutrinos produced via the Dodelson-Widrow (DW) mechanism, my colleagues and I investigated the constraints attainable for this mechanism by relaxing the usual hypothesis that the relic neutrino abundance must necessarily account for all of the dark matter. We firstly studied how to reinterpret the limits attainable from X-ray non-detection and Lyman-alpha forest measurements in the case that steril e neutrinos constitute only a fraction ‘f_s’ of the total amount of dark matter. Then, assuming that sterile neutrinos are generated in the early universe solely through the DW mechanism, we demonstrated how the X-ray and Lyman-alpha results jointly constrain the mass-mixing parameters governing their production. Furthermore, we showed how the same data allow us to set a robust upper limit of 0.7 at the 2 sigma level, rejecting the case of dominant dark matter (fs = 1) at the ~ 3 sigma level.