Observable features in ultrahigh energy neutrinos due to active-sterile secret interactions

We consider the effects of active-sterile secret neutrino interactions, mediated by a new pseudoscalar particle, on high and ultrahigh energy neutrino fluxes. In particular, we focus on the case of three active and one sterile neutrino coupled by a flavor dependent interaction, extending the case of one active and one sterile neutrino we have recently examined. We find that, depending on the kind of interaction of a sterile neutrino with the active sector, new regions of the parameter space for secret interactions are now allowed, with the masses of a sterile neutrino and scalar mediator ranging from 10 MeV to 1 GeV, leading to interesting phenomenological implications on two benchmark fluxes we consider, namely an astrophysical power law flux, in the range below 100 PeV, and a cosmogenic flux, in the ultrahigh energy range. First of all, the final active fluxes can present a measurable depletion observable in future experiments. Especially, in the case of only a ντ-νs interaction, we find that the effects on the astrophysical power law flux can be so large to be already probed by the IceCube experiment. Moreover, we find intriguing features in the energy dependence of the flavor ratio.