Interpretation of neutrino flux limits from neutrino telescopes on the Hillas plot

Abstract

We discuss the interplay between spectral shape and detector response beyond a simple E À2 neutrino flux at neutrino telescopes, using the example of time-integrated point source searches using IceCube-40 data. We use a self-consistent model for the neutrino production, in which protons interact with synchrotron photons from coaccelerated electrons, and we fully take into account the relevant pion and kaon production modes, the flavor composition at the source, flavor mixing, and magnetic field effects on the secondaries (pions, muon, and kaons). Since some of the model parameters can be related to the Hillas parameters R (size of the acceleration region) and B (magnetic field), we relate the detector response to the Hillas plane. In order to compare the response to different spectral shapes, we use the energy flux density as a measure for the pion production efficiency times luminosity of the source. We demonstrate that IceCube has a very good reach in this quantity for active galactic nuclei and jets for all source declinations, while the spectra of sources with strong magnetic fields are found outside the optimal reach. We also demonstrate where neutrinos from kaon decays and muon tracks from decays can be relevant for the detector response. Finally, we point out the complementarity between IceCube and other experiments sensitive to high-energy neutrinos, using the example of 2004-2008 Earth-skimming neutrino data from Auger. We illustrate that Auger, in principle, is more sensitive to the parameter region in the Hillas plane from which the highest-energetic cosmic rays may be expected in this model.

Neutrino decays over cosmological distances and the implications for neutrino telescopes

“…It is expected that the full scale experiment may detect neutrinos in such a case, but the interplay with the (energy-dependent) detector response becomes important (see ref. [71] for a more detailed discussion). For instance, better information may be obtained from down-going than upgoing muon tracks, because these exhibit a better sensitivity at higher energies (cf., figure 3 in ref.…”

“…For instance, better information may be obtained from down-going than upgoing muon tracks, because these exhibit a better sensitivity at higher energies (cf., figure 3 in ref. [71]). As a consequence, the sensitivity may be dominated by a different viewing window and therefore different bursts compared to the "no decay" case, which may have different characteristics.…”

Using High-Energy Neutrinos As Cosmic Magnetometers

“…In summary, if the average B is large, the synchrotron losses of protons and secondaries may visibly affect the spectral index α ν , flavor composition f α,⊕ , and maximum energy E max ν of the diffuse neutrino flux [66][67][68][69][70]. These features are softened and spread out in energy by the redshift distribution of the sources.…”

Unified thermal model for photohadronic neutrino production in astrophysical sources

“…Ref. [47]. In addition, the spectral shape, the relative number of each neutrino flavor produced, and the relative number of neutrinos and anti-neutrinos produced depend on the process in which they are produced (e.g.…”

“…Earlier works in this direction, such as Refs. [47,51,57], rely on a somewhat different assumption: there the target-photon spectrum is generated by synchrotron radiation off co-accelerated electrons -which also reduces the number of parameters, but is probably only a good approximation for specific source classes.…”