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Center for Nonlinear Studies |
Ever since the discovery of a flux of charged high-energy particles from space - called cosmic rays - their origins are unclear, particularly at the highest energies. Active Galactic Nuclei (AGN) and their relativistic outflows of plasma, called jets, are the favored counterpart for high-energy cosmic-rays. AGN are powered by supermassive black holes at the center of their host galaxies andfueled by accreting surrounding matter. AGN with their jet closely aligned with our line-of-sight are called blazars. They could accelerate protons to relativistic speeds, which are then detected atEarth. From the interactions of cosmic rays with photons, we also expect to observe neutrinos, which are not deflected by magnetic fieldsand are therefore ideal tracers of cosmic ray sources. With the recent detection of a cosmic neutrino flux, the search for the sources hasstarted.
One promising tool is the study of variability. So far, we have discovered two coincidences between a blazar outburst and the arrival of a high-energy neutrino, and I will discuss both cases in detail. I have further studied blazars consistent with IceCube neutrinos independent of outbursts. From the spectral energy distributions (SEDs) it is possible to calculate the estimated neutrino numbers of blazars. The resulting numbers are in good agreement with the observed neutrinoevents. Currently, supermassive black holes are the best candidates for the origin of the very and ultra-high energy cosmic-ray emission.
Host: Peter Polko, ppolko@lanl.gov