Guaranteed and prospective Galactic TeV neutrino sources

Abstract

Recent observations, particularly from the HESS Collaboration, have revealed rich Galactic populations of TeV gamma-ray sources, including a collection unseen in other wavelengths. Many of these gamma-ray spectra are well measured up to 10 TeV, where low statistics make observations by air Č erenkov telescopes difficult. To understand these mysterious sources, especially at much higher energies-where a cutoff should eventually appear -new techniques are needed. We point out the following: (1) For a number of sources, it is very likely that pions, and hence TeV neutrinos, are produced; (2) As a general point, neutrinos should be a better probe of the highest energies than gamma rays, due to increasing detector efficiency; and (3) For several specific sources, the detection prospects for km 3 neutrino telescopes are very good, 1-10 events/year, with low atmospheric neutrino background rates above reasonable energy thresholds. Such signal rates, as small as they may seem, will allow neutrino telescopes to powerfully discriminate between models for the Galactic TeV sources, with important consequences for our understanding of cosmic-ray production.

TeVγrays and neutrinos from photodisintegration of nuclei in Cygnus OB2

“…This is in complete contrast with the pp case where for an spectral index of 2 one expects on average a flux of ν µ half of that of γ-rays [83,84,85,86,87] (see Sec. V).…”

“…Hence, after taking into account oscillations, the ratio of muon and electron neutrinos plus antineutrinos to γ-rays of the same energy for α ∈ (1.5, 3) is approximately given by (and in good agreement with Refs. [83,84,85,86,87])…”

Enhanced cosmological GRB rates and implications for cosmogenic neutrinos

“…In order to produce a detectable signal, a particularly strong burst, with measured gamma-ray fluence * 3 10 ÿ4 erg cm ÿ2 (e.g., the recent GRBs 060928 [84] and 061007 [85], which were observed to have fluences very near this threshold) is required [62]. While the needed neutrino telescopes (which may also reveal the sources of Galactic cosmic rays [86]) are still under construction, future observations by Swift [56] should reveal similar bursts, in addition to determining the redshift-dependent GRB rate with unprecedented precision.…”

High Energy Astroparticle Physics

“…Indeed, all scenarios of cosmic ray origin, from the galactic scale [36] to top-down [37] and Z-burst models at the highest energies [40], are severely constrained by neutrino and γ−ray observations and limits. This has, for example, important consequences for theoretical predictions of diffuse fluxes of extragalactic neutrinos above about a TeV whose detection is a major goal of next-generation neutrino telescopes: If these neutrinos are produced as secondaries of protons accelerated in astrophysical sources and if these protons leave the sources and contribute to the UHECR flux observed, then the energy content in the neutrino flux can not be higher than the one in UHECRs, leading to the so called Waxman-Bahcall bound for transparent sources with soft acceleration spectra [41,42].…”