TeV and PeV Astrophysics with km3 Neutrino Telescopes, A Few Examples
The IceCube collaboration has recently reported the observation of two events with energies in excess of 1 PeV. While the atmospheric origin remains a possibility, this pair of showers may potentially represent the first observation of high-energy astrophysical neutrinos. I will argue that if these events are neutrino-induced, then they are likely to have been produced via photo-meson interactions taking place in the same class of astrophysical objects that are responsible for the acceleration of the eV cosmic ray spectrum.
Gamma-ray bursts stand out as particularly capable set of sources for the generation of PeV neutrinos at the level implied by IceCube's two events. In contrast, active galactic nuclei models due to their different radiation field properties have higher energy thresholds for pion production, leading to neutrino spectra which peak at EeV rather than PeV energies. Cosmogenic neutrinos generated from the propagation of ultra-high energy cosmic rays similarly peak at energies that are much higher than those of the events reported by IceCube. In contrast to PeV energies, no claims of astrophysical TeV neutrinos have been made yet.
The recent uncovering of the Fermi Bubbles/haze in the Fermi gamma-ray data has generated theoretical work to explain such a signal of hard gamma-rays in combination with the WMAP/Planck haze signal. Such include long time-scale star formation in the galactic center, DM annihilation, recent AGN jet activity, periodic diffusive shock acceleration, and stochastic 2nd order Fermi acceleration. Many of these theoretical models can have distinctively different implications with regards to the production of multi-TeV neutrinos. Some of these models will be probed by the IceCube DeepCore detector. Moreover, with a km$^3$ telescope located at the northern hemisphere, we will probe annihilation of TeV scale dark matter towards the galactic center.