Probing θ23 in neutrino telescopes

Among all neutrino mixing parameters, the atmospheric neutrino mixing angle θ23 introduces the strongest variation on the flux ratios of ultrahigh-energy neutrinos. We investigate the potential of these flux ratio measurements at neutrino telescopes to constrain θ23. We consider astrophysical neutrinos originating from pion, muon-damped, and neutron sources and make a comparative study of their sensitivity reach to θ23. It is found that neutron sources are most favorable for testing deviations from maximal θ23. Using a χ2 analysis, we show, in particular, the power of combining (i) different flux ratios from the same type of source, and also (ii) combining flux ratios from different astrophysical sources. We include in our analysis 'impure' sources, i.e., deviations from the usually assumed initial (1 ratio 2 ratio 0), (0 ratio 1 ratio 0), or (1 ratio 0 ratio 0) flux compositions