Measurement of Astrophysical Tau Neutrinos in IceCubes High-Energy Starting Events

We present the results of a search for astrophysical tau neutrinos in 7.5 years of IceCubes high-energy starting event data. At high energies, two energy depositions stemming from the tau neutrino charged-current interaction and subsequent tau lepton decay may be resolved. We report the first detection of two such events, with probabilities of $sim 76%$ and $sim 98%$ of being produced by astrophysical tau neutrinos. The resultant astrophysical neutrino flavor measurement is consistent with expectations, disfavoring a no-astrophysical tau neutrino flux scenario with 2.8$sigma$ significance.