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Seminars in Physics and Astronomy
The extremes of Neutrino Astronomy: From Fermi Bubbles with IceCube to Ice Studies with ARIANNA
by Lisa Unger (Uppsala University)
Thursday, 25 January 2018 from to (Europe/Stockholm)
The Fermi Bubbles are extended regions of hard gamma-ray emission which were discovered with Fermi-LAT data to exist above and below the Galactic Center. In order to explain the origin of the gamma-rays, different theories are proposed. In particular, within hadronic models, highly-accelerated cosmic rays interact with interstellar matter and create the observed gamma-rays and in addition neutrinos. An analysis method and the preliminary results of the study of a possible neutrino flux from the Fermi Bubbles using data from the neutrino detector IceCube will be described in this presentation. While this analysis is performed with the lowest energies IceCube can reach the ARIANNA (Antarctic Ross Ice-shelf ANtenna Neutrino Array) experiment has the goal to detect the highest energy neutrinos by measuring radio wave radiation produced by their interaction products in ice. With ARIANNA the propagation of radio waves in the firn (packed snow) of the Ross Ice-shelf was investigated. According to the classical approach the radio signal is supposed to bend down, because of the changing density, and therefore changing refractive index, in the firn, an effect which is called “shadowing”. Evidence that the waves can travel horizontally over a long distance will be presented.