High Energy Cosmic Tau Neutrinos

In this contribution i discuss the possibility of production of high energy cosmic tau neutrinos (E ≥ 10 GeV) in cores of Active Galactic Nuclei (AGN) originating from proton acceleration. The effects of three flavour neutrino mixing on this high energy cosmic tau neutrino flux and the prospects for its observations through double shower events [1]. In addition to AGNs, high energy cosmic tau neutrinos may also be produced in several currently envisaged other cosmologically distant astrophysical sources [2]. For some possible effects of neutrino mixing other than the flavour one on high energy cosmic tau neutrino flux, see [3]. For prospects of observations of high energy cosmic tau neutrinos other than the double shower technique, see [4]. The present study is particularly useful as several under water/ice high energy neutrino telescopes are now at their rather advanced stages of development and deployment [5]. I start in Section 2 with a brief description of possibility of production of high energy cosmic tau neutrinos relative to electron and muon neutrinos and discuss in some detail the effect of three flavour neutrino mixing on their subsequent propagation and further discuss the prospects for their detection through double shower events. In Section 3, i summarize the results.