Probing Extraterrestrial Neutrino Fluxes and Atmospheric Charm with Contained Neutrino Events above 1 TeV in IceCube

The IceCube Neutrino Observatory [1] was designed primarily to search for high-energy (100 TeV) neutrinos produced in distant astrophysical objects, and a search for high-energy neutrinos interacting inside the instrumented volume has recently provided evidence for a diffuse flux of such neutrinos [2]. Its energy threshold is however low enough to detect large numbers of neutrinos from the weak decays of pions and kaons produced in air showers; both the atmospheric νμ flux [3] and the sub-dominant atmospheric νe flux [4] have been observed by IceCube. A second, harder component of the atmospheric neutrino flux from decays of short-lived, charmed mesons in air showers has yet to be conclusively observed. Here, we present a strategy for extending the search for neutrino interactions in the instrumented volume down to ∼ 1 TeV and discuss the challenges of disentangling possible contributions of atmospheric charm decay from the high-energy extraterrestrial neutrino flux.