Probing for signs of neutrinos from heavy dark matter decay in the IceCube signal
As the IceCube has steadily collected data over the last several years, certain tensions have emerged between observations on one hand and fits obtained to these observations when assuming a single power-law diffuse astrophysical flux of neutrinos on the other; and between fits obtained using different kinds of datasets (HESE vs through-going muons). We analyse whether these tensions may be mitigated by the addition of a neutrino flux component originating from heavy (i.e. with masses above 100 TeV) dark matter decays possibly in addition to neutrinos from astrophysical sources modeled by an isotropic power-law. To this end, we perform a detailed analysis of the HESE event samples (considering simultaneously the energy, hemisphere and topology of the events) by fitting the mass and lifetime of the dark matter and the normalization and spectral index of an isotropic power-law flux, for various decay channels of dark matter. We find that such a two-component flux is favoured by recent data at IC, and discuss the trends of these fits over the years. We also discuss if the signal at IC could be explained by neutrinos purely from dark matter decays (i.e. without astrophysical neutrinos), in cases where decays proceed via multiple channels.