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Growing observational evidence suggests that enhanced mass loss from the progenitors of core-collapse supernovae (SNe) is common during $\sim1$ yr preceding the explosion, creating an optically thick circum-stellar medium (CSM) shell at $\sim10^{14.5}$ cm radii. We show that if such mass loss is indeed common, then the breakout of the SN shock through the dense CSM shell produces a neutrino flux that may account for a significant fraction of the observed $\gtrsim10$ TeV neutrino background. The neutrinos are created within a few days from the explosion, during and shortly after the shock breakout, which produces also large UV (and later X-ray) luminosity. The compact size and large UV luminosity imply a pair production optical depth of $\sim10^4$ for $>100$ GeV photons, naturally accounting for the lack of a high-energy gamma-ray background accompanying the neutrino background. SNe producing $>1$ neutrino event in a 1 km$^2$ detector are expected at a rate of $\lesssim0.1$/yr. A quantitative theory describing the evolution of the electromagnetic spectrum during a breakout, as the radiation-mediated shock is transformed into a collisionless one, is required to enable (i) using data from upcoming surveys that will systematically detect large numbers of young, $<1$ d old SNe, to determine the pre-explosion mass loss history of the SN progenitor population, and (ii) a quantitative determination of the neutrino luminosity and spectrum., Comment: Accepted to ApJ. Added discussion of current IceCube limits and non-type II SNe contribution

The IceCube collaboration reports a detection of extra-terrestrial neutrinos. The isotropy and flavor content of the signal, and the coincidence, within current uncertainties, of the 50 TeV to 2 PeV flux and the spectrum with the Waxman-Bahcall bound, suggest a cosmological origin of the neutrinos, related to the sources of ultra-high energy, $>10^{10}$ GeV, cosmic-rays (UHECR). The most natural explanation of the UHECR and neutrino signals is that both are produced by the same population of cosmological sources, producing CRs (likely protons) at a similar rate, $E^2d\dot{n}/dE\propto E^{0}$, over the [$1$ PeV,$10^{11}$ GeV] energy range, and residing in "calorimetric" environments, like galaxies with high star formation rate, in which $E/Z<100$ PeV CRs lose much of their energy to pion production. A tenfold increase in the effective mass of the detector at $\gtrsim100$ TeV is required in order to significantly improve the accuracy of current measurements, to enable the detection of a few bright nearby starburst "calorimeters", and to open the possibility of identifying the CR sources embedded within the calorimeters, by associating neutrinos with photons accompanying transient events responsible for their generation. Source identification and a large neutrino sample may enable one to use astrophysical neutrinos to constrain new physics models., Comment: To appear in "Neutrino Astronomy- Current status, future prospects", Eds. T. Gaisser & A. Karle (World Scientific)

The flux, spectrum and angular distribution of the excess neutrino signal detected by IceCube between 50TeV and 2PeV are inconsistent with those expected for Galactic sources. The coincidence of the excess, $E_\nu^2\Phi_\nu=3.6\pm1.2\times10^{-8}(GeV/ cm^2 sr s)$, with the Waxman-Bahcall (WB) bound, $E_\nu^2\Phi_{WB}=3.4\times10^{-8}(GeV/cm^2 sr s)$, is probably a clue to the origin of IceCube's neutrinos. The most natural explanation of this coincidence is that both the neutrino excess and the ultra-high energy, $>10^{19}$ eV, cosmic-ray (UHECR) flux are produced by the same population of cosmologically distributed sources, producing CRs, likely protons, at a similar rate, $E^2 dQ/dE=0.5\times10^{44}(erg/Mpc^3yr)$ (at z=0), across a wide range of energies, from $10^{15}$ eV to $>10^{20}$ eV, and residing in environments (such as starburst galaxies) in which CRs of rigidity $E/Z< 10^{17}$ eV lose much of their energy to pion production. Identification of the neutrino sources will allow one to identify the UHECR accelerators, to resolve open questions related to the accelerator models, and to study neutrino properties (related e.g. to flavor oscillations and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible. The most promising method for identifying the sources is by association of a neutrino with an electromagnetic signal accompanying a transient event responsible for its generation. The neutrino flux that is produced within the sources, and that may thus be directly associated with transient events, may be significantly lower than the total observed neutrino flux, which may be dominated by neutrino production at the environment in which the sources reside., Comment: 8 pages, 2 figures, to appear in the Proc. of the 9th Rencontres du Vietnam : Windows on the universe

Cosmic-rays with energies exceeding 10^{19} eV are referred to as Ultra High Energy Cosmic Rays (UHECRs). The sources of these particles and their acceleration mechanism are unknown, and for many years have been the issue of much debate. The first part of this review describes the main constraints, that are implied by UHECR observations on the properties of candidate UHECR sources, the candidate sources, and the related main open questions. In order to address the challenges of identifying the UHECR sources and of probing the physical mechanisms driving them, a "multi-messenger" approach will most likely be required, combining electromagnetic, cosmic-ray and neutrino observations. The second part of the review is devoted to a discussion of high energy neutrino astronomy. It is shown that detectors, which are currently under construction, are expected to reach the effective mass required for the detection of high energy extra-Galactic neutrino sources, and may therefore play a key role in the near future in resolving the main open questions. The detection of high energy neutrinos from extra-Galactic sources will not only provide constraints on the identity and underlying physics of UHECR sources, but may furthermore provide information on fundamental neutrino properties., Comment: 16 pages, 10 figures; To be published in {\guillemotleft} Astronomy at the Frontiers of Science {\guillemotright}, ed. J.-P. Lasota, Springer 2011. The original publication will be available at http://www.springerlink.com

The construction of large volume detectors of high energy, >1 TeV, neutrinos is mainly driven by the search for extra-Galactic neutrino sources. The existence of such sources is implied by observations of ultra-high energy, >10^{19} eV, cosmic-rays, the origin of which is a mystery. In this lecture I briefly discuss the expected extra-Galactic neutrino signal and the current state of the experimental efforts. Neutrino emission from gamma-ray bursts (GRBs), which are likely sources of both high energy protons and neutrinos, is discussed in some detail. The detection of the predicted GRB neutrino signal, which may become possible in the coming few years, will allow one to identify the sources of ultra-high energy cosmic-rays and to resolve open questions related to the underlying physics of GRB models. Moreover, detection of GRB neutrinos will allow one to test for neutrino properties (e.g. flavor oscillations and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible., Comment: Review, R. Soc. Discussion Meeting on GRBs (To appear in Phil. Trans. R. Soc. Lond. A)

In the past four decades a new type of astronomy has emerged, where instead of looking up into the sky "telescopes" are buried miles underground or deep under water or ice and search not for photons (that is, light), but rather for particles called neutrinos. Neutrinos are nearly massless particles that interact very weakly with matter. The detection of neutrinos emitted by the Sun and by a nearby supernova provided direct tests of the theory of stellar evolution and led to modifications of the standard model describing the properties of elementary particles. At present, several very large neutrino detectors are being constructed, aiming at the detection of the most powerful sources of energy and particles in the universe. The hope is that the detection of neutrinos from these sources, which are extra-Galactic and are most likely powered by mass accretion onto black-holes, will not only allow study of the sources, but, much like solar neutrinos, will also provide new information about fundamental properties of matter., Comment: Perspective article, Science Special Issue on "particle astrophysics" (Jan 2007)

The existence of cosmic rays of energies exceeding 10^20 eV is one of the mysteries of high energy astrophysics. The spectrum and the high energy to which it extends rule out almost all suggested source models. The challenges posed by observations to models for the origin of high energy cosmic rays are reviewed, and the implications of recent new experimental results are discussed. Large area high energy cosmic ray detectors and large volume high energy neutrino detectors currently under construction may resolve the high energy cosmic ray puzzle, and shed light on the identity and physics of the most powerful accelerators in the universe., Comment: 12 pages, 7 figures; Summary of review talk, PASCOS 03 (Mumbai, India)

Several high energy, >100 GeV, neutrino telescopes are currently operating or under construction. Their main motivation is the extension of the horizon of neutrino astronomy to cosmological scales. We show that general, model independent, arguments imply that ~1 Gton detectors are required to detect cosmic high energy neutrino sources. Predictions of models of some of the leading candidate sources, gamma-ray bursts and micro-quasars, are discussed, and the question of what can be learned from neutrino observations is addressed., Comment: Invited talk, Neutrino 2002 (Munich)

The suggested association between the sources of gamma-ray bursts (GRB's) and the sources of ultra-high energy cosmic rays (UHECR's) is based on two arguments: (i) The average energy generation rate of UHECR's is similar to the gamma-ray generation rate of GRB's, and (ii) The constraints that UHECR sources must satisfy to allow proton acceleration to >10^{20} eV are similar to those inferred for GRB sources from gamma-ray observations. We show that recent GRB and UHECR observations strengthen both arguments, and hence strengthen the suggested association., Comment: Arguments strengthened by the inclusion of updated constraints on GRB rate and model parameters, based on new afterglow data and analysis. Accepted to ApJ

Magnetars can accelerate cosmic rays to high energies through the unipolar effect, and are also copious soft photon emitters. We show that young, fast-rotating magnetars whose spin and magnetic moment point in opposite directions emit high energy neutrinos from their polar caps through photomeson interactions. We identify a neutrino cut-off band in the magnetar period-magnetic field strength phase diagram, corresponding to the photomeson interaction threshold. Within uncertainties, we point out four possible neutrino emission candidates among the currently known magnetars, the brightest of which may be detectable for a chance on-beam alignment. Young magnetars in the universe would also contribute to a weak diffuse neutrino background, whose detectability is marginal, depending on the typical neutrino energy., Comment: emulateapj style, 6 pages, 1 figure, ApJ, v595, in press. Important contributions from Dr. Harding added. Major revisions made. More conservative and realistic estimates about the neutrino threshold condition and emission efficiency performed. More realistic typical beaming angle and magnetar birth rate adopted

We discuss the possibility that microquasar jets may be powerful emitters of TeV neutrinos. We estimate the neutrino fluxes produced by photopion production in the jets of a sample of identified microquasars and microquasar candidates, for which available data enables rough determination of the jet parameters. We demonstrate that in several of the sources considered, the neutrino flux at Earth, produced in events similar to those observed, can exceed the detection threshold of a km^2 neutrino detector. Sources with bulk Lorentz factors larger than those characteristic of the sample considered here, directed along our line of sight may be very difficult to resolve at radio wavelengths and hence may be difficult to identify as microqusar candidates. However these sources can be identified through their neutrino and gamma-ray emission., Comment: To appear in the Proceedings of the 4th Microquasar Workshop, 2002, eds. Durouchoux, Fuchs & Rodriguez, published by the Center for Space Physics: Kolkata

It has been proposed recently that Galactic microquasars may be prodigious emitters of TeV neutrinos that can be detected by upcoming km^2 neutrino telescopes. In this paper we consider a sample of identified microquasars and microquasar candiates, for which available data enables rough determination of the jet parameters. By employing the parameters inferred from radio observations of various jet ejection events, we determine the neutrino fluxes that should have been produced during these events by photopion production in the jet. Despite the large uncertainties in our analysis, we demonstrate that in several of the sources considered, the neutrino flux at Earth, produced in events similar to those observed, would exceed the detection threshold of a km^2 neutrino detector. The class of microquasars may contain also sources with bulk Lorentz factors larger than those characteristic of the sample considered here, directed along our line of sight. Such sources, which may be very difficult to resolve at radio wavelengths and hence may be difficult to identify as microqusar candidates, may emit neutrinos with fluxes significantly larger than typically obtained in the present analysis. These sources may eventually be identified through their neutrino and gamma-ray emission., Comment: 17 pages. Submitted to ApJ

Core collapse of massive stars resulting in a relativistic fireball jet which breaks through the stellar envelope is a widely discussed scenario for gamma-ray burst production. For very extended or slow rotating stars, the fireball may be unable to break through the envelope. Both penetrating and choked jets will produce, by photo-meson interactions of accelerated protons, a burst of neutrinos with energies in excess of 5 TeV while propagating in the envelope. The predicted flux, from both penetrating and chocked fireballs, should be easily detectable by planned cubic kilometer neutrino telescopes., Comment: Phys.Rev.Letters, in press, final version accepted 8/31/01 (orig. 3/17/01)

Observations imply that gamma-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a highly relativistic fireball. Photo-meson interactions of protons with gamma-rays within the fireball dissipation region are expected to convert a significant fraction of fireball energy to >10^14 eV neutrinos. We present an analysis of the internal shock model of GRBs, where production of synchrotron photons and photo-meson neutrinos are self-consistently calculated, and show that the fraction of fireball energy converted to high energy neutrinos is not sensitive to uncertainties in fireball model parameters, such as the expansion Lorentz factor and characteristic variability time. This is due in part to the constraints imposed on fireball parameters by observed GRB characteristics, and in part to the fact that for parameter values for which the photo-meson optical depth is high (implying high proton energy loss to pion production) neutrino production is suppressed by pion and muon synchrotron losses. The neutrino flux is therefore expected to be correlated mainly with the observed gamma-ray flux. The time averaged neutrino intensity predicted by the model, ~10^-8.5 GeV/cm^2 s sr, is consistent with the flux predicted by the assumption that GRBs are the sources of >10^19 eV cosmic-rays., Comment: 17 pages, 7 ps-figures. Submitted to ApJ

Ultra-high-energy, >10^19 eV, cosmic-ray and high energy, ~10^14 eV, neutrino production in GRBs is discussed in the light of recent GRB and cosmic-ray observations. Emphasis is put on model predictions that can be tested with operating and planned cosmic-ray and neutrino detectors, and on the prospects of testing for neutrino properties., Comment: 7 pages; Invited talk presented at the 7th International Symposium on Particles, Strings and Cosmology (Dec. 1999, Lake Tahoe, California)

The gamma-ray burst (GRB) model for production of ultra-high-energy cosmic-rays (UHECRs) is based on the hypothesis that GRBs arise from the dissipation of the kinetic energy of relativistic fireballs at cosmological distances. Recent GRB afterglow observations support the validity of this hypothesis and provide quantitative support for the model. The inferred physical fireball parameters imply that protons may be accelerated to >10^20 eV, and the inferred GRB energy generation rate is similar to that required to account for the observed flux of UHECRs. Strong suppression of UHECR flux is expected in this model above 10^19.7 eV, due to proton interaction with CMB photons. Strong deviations from model flux derived under the assumption of uniform source distribution is expected above 10^20 eV, due to source clustering. The flux above 10^20.5 eV is expected to be dominated by few, narrow spectrum sources. While model predictions can not be tested (with high confidence level) at present, the predicted signatures should be observed with the planned Auger and Telescope-Array UHECR detectors. A natural consequence of the GRB model of UHECR production is the conversion of a large fraction, ~10%, of the fireball energy to accompanying burst of \~10^14 eV and ~10^18 eV neutrinos. A km^2 neutrino detector would observe several tens of events per year correlated with GRBs, and test for neutrino properties (e.g. flavor oscillations, for which upward moving tau's would be a unique signature, and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible., Comment: 10 pages; in press, Proc. TAUP99 [Nucl. Phys. B (Proc. Suppl.)], ed. M. Froissart, J. Dumarchez and D. Vignaud