Implications of AMANDA neutrino flux limits

The Antarctic Muon And Neutrino Detector Array (AMANDA) is currently the most sensitive neutrino telescope at high energies. Data have been collected in a period of eight years and analyzed with different analysis strategies. Limits to the neutrino flux from point sources, transient emissions, source catalogs and limits to different diffuse flux models have been obtained implying in some cases strong constraints to hadronic interaction models of such sources. In this contribution, implications of the diffuse neutrino limit will be discussed with respect to neutrino production mechanisms in astrophysical sources. 1. Neutrino flux predictions The existence of Ultra High Energy Cosmic Rays (UHECRs) as well as the detection of TeV photon emissions from galactic and extragalactic sources are a strong indication for neutrino (ν) emission from the same sources. Pions and kaons are believed to take a fraction of the proton energy producing TeV photons in coincidence with high energy neutrinos. Although the atmospheric background of neutrinos is quite high, it decreases rapidly with energy (∼ E) while the extraterrestrial spectra of galactic and extra-galactic sources are typically flatter (typically ∼ E if shock acceleration is the main mechanism producing high energetic protons at the source). The latter should therefore become the dominant component of the total diffuse spectrum at a certain energy, which depends on the normalization of the neutrino flux. Different predictions are shown in Fig. ??. The left panel shows various calculations which use the diffuse X-ray background as measured by ROSAT to normalize the neutrino spectrum, see [?, ?]. This is justified when assuming the production of neutrinos along with X-rays at the foot of jets of Active Galactic Nuclei (AGN) where protons are accelerated into the photon target of the disk. The right panel shows models based on the correlation between UHECRs, TeV photons and neutrinos, see [?, ?]. Such sources are optically thin to both TeV photons and protons. 2. Detection techniques of AMANDA AMANDA detects muon-neutrinos (νμs) by observing secondary muons from charged current interactions of the neutrinos with the nucleons of the ice. The muons are traveling faster than light in ice and emit Cherenkov radiation which is detected by the photomultiplier tubes. Between the years 2000 and 2004 data from effectively 1001 days have been taken and a νμ sample of 4282 events from the Northern hemisphere has been collected. In order to keep 1 http://icecube.wisc.edu and these proceedings 2 Atmospheric muons make it impossible to use the Southern hemisphere for νμ searches. Cascade analyses can, however, be done for both hemispheres. These results will not be discussed here, but can be found in e.g. [?] diffuse limit (00-03) log(Eν /GeV) Φ E ν 2 [G eV sr -1 s 1 c m -2 ]