The Pierre Auger observatory has presented evidence that the arrival directions of cosmic rays with energies in excess of 6x10^7 TeV may be correlated with nearby active galactic nuclei (AGN). In this context we revisit a suggestion based on gamma ray observations that nearby Fanaroff-Riley I galaxies such as Cen A and M87 are the sources of the local cosmic rays. We compute the accompanying neutrino flux and find a flux within reach of second-generation kilometer-scale neutrino telescopes.
We discuss the main results that were recently published by the Auger Collaboration and their impact on our knowledge of the ultra high energy cosmic rays and neutrinos.
The Pierre Auger Observatory has the capability of detecting neutrino-induced extensive air showers by searching for very inclined showers with a significant electromagnetic component. In order to study the detector response of the surface array of the Pierre Auger Observatory, Monte Carlo simulations of up-going and down-going neutrino showers for all flavors were performed. A set of relevant observables were determined to discriminate these showers from the background of very inclined hadronic showers and the identification efficiency was studied. The acceptance and the expected event rates,…
With the Pierre Auger Observatory we have the capability of detecting ultra-high energy neutrinos by searching for very inclined showers with a significant electromagnetic component. In this work we discuss the discrimination power of the instrument for earth skimming tau neutrinos with ultra-high energies. Based on the data collected since January 2004 an upper limit to the diffuse flux of neutrinos atEeV energies is presented and systematic uncertainties are discussed.
We present a study about the possibility to detect neutrino induced extensive air showers at the Pierre Auger Observatory. The Monte Carlo simulations performed take into account the details of the neutrino propagation inside the Earth, the air as well as the surrounding mountains which are modelled by a digital elevation map. Details on the sensitivity with respect to the incoming direction as well as the aperture and the total observable event rates are calculated on the basis of various assumptions of the incoming neutrino flux.
Ultra high energy neutrinos are produced by the interaction of hadronic cosmic rays with the cosmic radiation background. More exotic scenarios like topological defects or new hadrons predict even larger fluxes. In particular, Earth-skimming tau neutrinos could be detected by the Fluorescence Detector (FD) of Pierre Auger Observatory. A detailed evaluation of the expected number of events has been performed for a wide class of neutrino flux models. An updated computation of the neutrino-nucleon cross section and of the tau energy losses has been carried out. For the most optimistic theoretical…
Detection of Ultra High Energy Neutrinos (UHEN), with energy above 0.l EeV (10**18 eV) is one of the most exciting challenges of high energy astrophysics and particle physics. In this article we show that the Auger Observatories, built to study ultra high energy cosmic rays, are one of the most sensitive neutrino telescopes that will be available in the next decade. Furthermore, we point out that the Waxman-Bahcall upper bound for high energy neutrino fluxes below 1 EeV turns into a lower bound above a few EeV. In this framework and given the experimental evidences for nu_mu <--> nu_tau oscill…
It is anticipated that the Pierre Auger Observatory can be used to detect cosmic neutrinos of >10^19 eV that arrive at very large zenith angles. However showers created by neutrino interactions close to the detector must be picked out against a background of similar events initiated by cosmic ray nuclei. As a step towards understanding this background, we have made the first detailed analysis of air showers recorded at Haverah Park (an array which used similar detectors to those planned for the Auger Observatory) with zenith angles above 60 degs. We find that the differential shower rate from …
The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau-neutrinos $ν_τ$ that interact in the Earth's crust. Tau leptons from $ν_τ$ charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 is used to place an upper limit on the diffuse flux of $ν_τ$ at EeV energies. Assuming an $E_ν^{-2}$ differential energy spectrum the limit set at 90 % C.L. is $E_ν^{2} \mathrm{d}N_{ν_τ}/\mathrm{d}E_ν < 1.3 \times 10^{…
Earth--skimming UHE tau neutrinos have a chance to be detected by the Fluorescence Detector (FD) of Pierre Auger Observatory if their astrophysical flux is large enough. A detailed evaluation of the expected number of events is here performed for a wide class of neutrino flux models.
We study the potential of the Pierre Auger detector for horizontal air showers initiated by ultra high energy neutrino. Assuming some simple trigger requirements we obtain measurable event rates for neutrino fluxes from AGN, from topological defects and from the interactions of cosmic rays with the microwave background.
The cosmic ray spectrum has been shown to extend well beyond 10^{20}eV. With nearly 20 events observed in the last 40 years, it is now established that particles are accelerated or produced in the universe with energies near 10^{21}eV. In all production models neutrinos and photons are part of the cosmic ray flux. In acceleration models (bottom-up models), they are produced as secondaries of the possible interactions of the accelerated charged particle; in direct production models (top-down models) they are a dominant fraction of the decay chain. In addition, hadrons above the GZK threshold en…
The Pierre Auger collaboration has reported a correlation between Ultra-High Energy Cosmic Rays (UHECR) and nearby Active Galactic Nuclei (AGNs) within 75 Mpc. Two of these events fall within 3 degrees from Centaurus A, the nearest AGN, clearly suggesting that this object is a strong UHECR emitter. Here we pursue this hypothesis and forecast the expected rate of ultra-high energy neutrinos in detectors like IceCube. In our baseline model we find a rate of 0.4--0.6 yr^-1 events above a threshold of 100 TeV, the uncertainty of which is mainly related to the poor knowledge of the physical paramet…
We show that the Auger Air Shower Array has the potential to detect neutrinos of energies in the $10^{19}~$eV range through horizontal air showers. Assuming some simple conservative trigger requirements we obtain the acceptance for horizontal air showers as induced by high energy neutrinos by two alternative methods and we then give the expected event rates for a variety of neutrino fluxes as predicted in different models which are used for reference.
The Pierre Auger Observatory for cosmic rays provides a laboratory for studying fundamental interactions at energies well beyond those available at colliders. In addition to hadrons or photons, Auger is sensitive to ultra-high energy neutrinos in the cosmic radiation and models for new physics can be explored by observing neutrino interactions at center-of-mass energies beyond the TeV scale. By comparing the rate for quasi-horizontal, deeply penetrating air showers triggered by all types of neutrinos with the rate for slightly upgoing showers generated by Earth-skimming tau neutrinos, any devi…
We perform a new study of the chances of the fluorescence detector (FD) at the Pierre Auger Observatory to detect the tau leptons produced by Earth-skimming ultra high energy tau neutrinos. We present a new and more detailed evaluation of the effective aperture of the FD that considers a reliable fiducial volume for the experimental set up. In addition, we take into account the real elevation profile of the area near Auger. We find a significant increase in the number of expected events with respect to the predictions of a previous semi-analytical determination, and our results show the enhanc…
The sources of the observed ultra-high energy cosmic rays must also generate ultra-high energy neutrinos. Deep inelastic scattering of these neutrinos with nucleons on Earth probe center-of-mass energies $\sqrt{s} \sim 100$ TeV, well beyond those attainable at terrestrial colliders. By comparing the rates for two classes of observable events, any departure from the benchmark (unscreened perturbative QCD) neutrino-nucleon cross-section can be constrained. Using the projected sensitivity of the Pierre Auger Observatory to quasi-horizontal showers and Earth-skimming tau neutrinos, we show that a …
The Auger project was designed to study the high-energy cosmic rays by measuring the properties of the showers produced in the atmosphere. The Southern Auger Observatory has taken data since January 2004 and is now completed. Results on mass composition, energy spectrum and anisotropy of the arrival directions are presented together with upper limits on the neutrino fraction. The most important result is the recent observation of correlations with nearby extragalactic objects.
The author reviews a model for the emission of high energy cosmic rays, gamma-rays and neutrinos from AGN (Active Galactic Nuclei) that he has proposed since 1985. Further discussion of the knee energy phenomenon of the cosmic ray energy spectrum requires the existence of a heavy particle with mass in the knee energy range. A possible method of detecting such a particle in the Pierre Auger Project is suggested. Also presented is a relation between the spectra of neutrinos and gamma-rays emitted from AGN. This relation can be tested by high energy neutrino detectors such as ICECUBE, the Mediter…
The Pierre Auger Observatory can detect with high efficiency the air showers induced by ultra-high energy cosmic rays incident at large (> 60 deg.) zenith angles. We describe here the specific characteristics of inclined and horizontal showers, as well as the characteristics of their signal in the surface detector. We point out their relevance both to extend the potential of the detector, and in the context of the detection of high-energy cosmic neutrinos.
The focus of this article is on recent results on ultra-high energy cosmic rays obtained with the Pierre Auger Observatory. The world's largest instrument of this type and its performance are described. The observations presented here include the energy spectrum, the primary particle composition, limits on the fluxes of photons and neutrinos and a discussion of the anisotropic distribution of the arrival directions of the most energetic particles. Finally, plans for the construction of a Northern Auger Observatory in Colorado, USA, are discussed.
Taking into account the Pierre Auger Observatory limits on the photon fraction among the highest energy cosmic rays, we show that the models based on the decay of super-heavy dark matter in the halo of our Galaxy are essentially excluded from being the sources of UHECRs unless their contribution becomes significant only above 100 EeV. Some top-down models based on topological defects are however compatible with the current data and may be best constrained in the future by the high-energy neutrino flux limit.
The Pierre Auger Observatory (PAO) has measured the spectrum and composition of the ultrahigh energy cosmic rays with unprecedented precision. We use these measurements to constrain their spectrum and composition as injected from their sources and, in turn, use these results to estimate the spectrum of cosmogenic neutrinos generated in their propagation through intergalactic space. We find that the PAO measurements can be well fit if the injected cosmic rays consist entirely of nuclei with masses in the intermediate (C, N, O) to heavy (Fe, Si) range. A mixture of protons and heavier species is…
The origin of ultra-high energy cosmic rays is discussed in light of the latest observational results from the Pierre Auger Observatory, highlighting potential astrophysical sources such as active galactic nuclei, gamma-ray bursts, and clusters of galaxies. Key issues include their energy budget, the acceleration and escape of protons and nuclei, and their propagation in extragalactic radiation and magnetic fields. We briefly address the prospects for Telescope Array and future facilities such as JEM-EUSO, and also emphasize the importance of multi-messenger X-ray and gamma-ray signatures in a…
The Southern Pierre Auger Observatory is now nearing completion and the accumulating data sample has already allowed to extract scientific results of relevance for ultra-high energy cosmic-ray (UHECR) physics. This lecture focuses on the description and outcomes of the studies on the UHECR arrival directions (and in particular the anisotropy searches around the Galactic Center) and composition (with the extraction of a limit on the flux of UHE photons and its implications). Perspectives concerning the study of inclined showers and the potential of detection of UHE neutrinos are also briefly di…
We examine the effects of resonant Auger destruction in modifying the intensities and flux distributions of K-alpha spectra from iron L-shell ions. Applications include X-ray irradiated stellar winds in X-ray binaries and accretion disk atmospheres. Using detailed atomic models, we find that resonant Auger destruction is selective, in that only a subset of the emitted K-alpha lines is highly attenuated. We also show that that the local excitation conditions can have a dramatic effect on the K-alpha emissivity spectrum.
Absolute calibration of the Pierre Auger Observatory fluorescence detectors uses a light source at the telescope aperture. The technique accounts for the ombined effects of all detector components in a single measurement. The calibrated 2.5 m diameter light source fills the aperture, providing uniform illumination to each pixel. The known flux from the light source and the response of the acquisition system give the required calibration for each pixel. In the lab, light source uniformity is studied using CCD images and the intensity is measured relative to NIST-calibrated photodiodes. Overall …
We fit the recently published Pierre Auger ultra-high energy cosmic ray spectrum assuming that either nucleons or nuclei are emitted at the sources. We consider the simplified cases of pure proton, or pure oxygen, or pure iron injection. We perform an exhaustive scan in the source evolution factor, the spectral index, the maximum energy of the source spectrum Z E_{max}, and the minimum distance to the sources. We show that the Pierre Auger spectrum agrees with any of the source compositions we assumed. For iron, in particular, there are two distinct solutions with high and low E_{max} (e.g. 6.…
Many models for ultra-high energy cosmic rays postulate exotic scenarios to explain the sources or the nature of these particles. A characteristic feature of these models is the prediction of a significant flux of photons at ultra-high energy. The Pierre Auger Observatory offers a great potential to search for such photons. We present shower observables with sensitivity to photons and the search strategy employed. An upper limit to photon primaries is derived from first Auger data. Prospects for constraining theoretical source models are discussed.
The main results from the Auger Observatory are described. A steepening of the spectrum is observed at the highest energies, supporting the expectation that above $4\times 10^{19}$ eV the cosmic ray energies are significantly degraded by interactions with the CMB photons (the GZK effect). This is further supported by the correlations observed above $6\times 10^{19}$ eV with the distribution of nearby active galaxies, which also show the potential of Auger to start the era of charged particle astronomy. The lack of observation of photons or neutrinos strongly disfavors top-down models, and thes…
We study about ultra-high-energy cosmic rays (UHECRs) from transient sources, propagating in the Galactic and intergalactic space. Based on the recent observational results, we also estimate upper and lower bounds on the rate of transient UHECR sources and required isotropic cosmic-ray energy input per burst as 0.1 Gpc^-3 yr^-1 < rho_0 < 10^3.5 Gpc^-3 yr^-1 and 10^49.5 ergs < E_HECR^iso < 10^54 ergs, through constraining the apparent burst duration, i.e., dispersion in arrival times of UHECRs. Based on these bounds, we discuss implications for proposed candidates such as gamma-ray bursts and a…
We study the small scale anisotropy signal expected at the Pierre Auger Observatory in the next 1, 5, 10, and 15 years of operation, from sources of ultra-high energy (UHE) protons. We numerically propagate UHE protons over cosmological distances using an injection spectrum and normalization that fits current data up to $\sim 10^{20}\eV$. We characterize possible sources of ultra-high energy cosmic rays (UHECRs) by their mean density in the local Universe, $\barρ = 10^{-r}$ Mpc$^{-3}$, with $r$ between 3 and 6. These densities span a wide range of extragalactic sites for UHECR sources, from co…
We analyze the active-galaxy correlation reported in 2007 by the Pierre Auger Collaboration. The signal diminishes if the correlation-function approach (counting all "source-event" pairs and not only "nearest neighbours") is used, suggesting that the correlation may reveal individual sources and not their population. We analyze available data on physical conditions in these individual correlated sources and conclude that acceleration of protons to the observed energies is hardly possible in any of these galaxies, while heavier nuclei would be deflected by the Galactic magnetic field thus spoil…
We perform an autocorrelation study of the Auger data with the aim to constrain the number density n_s of ultrahigh energy cosmic ray (UHECR) sources, estimating at the same time the effect on $n_s$ of the systematic energy scale uncertainty and of the distribution of UHECR. The use of global analysis has the advantage that no biases are introduced, either in n_s or in the related error bar, by the a priori choice of a single angular scale. The case of continuous, uniformly distributed sources is nominally disfavored at 99% C.L. and the fit improves if the sources follow the large-scale struct…
The cosmic ray spectrum has been shown to extend well beyond 10^20 eV. With nearly 20 events observed in the last 40 years, it is now established that particles are accelerated or produced in the universe with energy near 10^21 eV. In all production models neutrinos and photons are part of the cosmic ray flux. In acceleration models (bottom-up models), they are produced as secondaries of the possible interactions of the accelerated charged particle, in direct production models (top-down models) they are a dominant fraction of the decay chain. In addition, hadrons above the GZK threshold energy…
Motivated by recent Pierre Auger result on the correlation of the highest-energy cosmic rays with the nearby active galactic nuclei, we explore possible ultrahigh energy cosmic ray (UHECR) source distributions and their effects on GZK horizons. Effects on GZK horizons by local over-density of UHECR sources are examined carefully with constraints on the degree of local over-density inferred from the measured UHECR spectrum. We include the energy calibration effect on the Pierre Auger data in our studies. We propose possible local over-densities of UHECR sources which are testable in the future …
We measured the Cerenkov signal fluctuations in the water tanks of the Pierre Auger Observatory. Two stations located near the center of the 32-tank Engineering Array separated by 11 m were used for the purpose. At this separation the stations sample nearly the same region of the air shower. Sources of the signal fluctuations are discussed.
We consider the hypothesis that luminous infrared galaxies (LIRGs) are sources of the UHECRs. By associating the AGASA triplet with the Arp 299 galaxy we obtain reasonable values for Galactic and extragalactic magnetic fields. We predict what the southern sky, to be seen by the Auger experiment, should look like, so that the LIRG hypothesis could be verified soon.
The existence of extra degrees of freedom beyond the electroweak scale may allow the formation of black holes in nearly horizontal neutrino air showers. In this paper we examine the average properties of the light descendants of these black holes. Our analysis indicates that black hole decay gives rise to deeply penetrating showers with an electromagnetic component which differs substantially from that in conventional neutrino interactions, allowing a good characterization of the phenomenon against background. Naturally occurring black holes in horizontal neutrino showers could be detected and…
The discoveries of the GZK cutoff with the HiRes and Auger Observatories and the discovery by Auger of clustering of >~60 EeV ultra-high energy cosmic rays (UHECRs) towards nearby <~75 Mpc) AGNs along the supergalactic plane establishes the astrophysical origin of the UHECRs. The likely sources of the UHECRs are gamma-ray bursts and radio-loud AGNs because: (1) they are extragalactic; (2) they are sufficiently powerful; (3) acceleration to ultra-high energies can be achieved in their relativistic ejecta; (4) anomalous X-ray and gamma-ray features can be explained by nonthermal hadron accelerat…
We present a method to measure the relative spectral response of the Pierre Auger Observatory Fluorescence Detector. The calibration was done at wavelengths of 320, 337, 355, 380 and 405 nm using an end-to-end technique in which the response of all detector components are combined in a single measurement. A xenon flasher and notch-filters were used as the light source for the calibration device. The overall uncertainty is 5%.
A key step towards the understanding of the origin of ultra-high energy cosmic rays is their mass composition. Primary photons and neutrinos produce markedly different showers from nuclei, while showers of different nuclear species are not easy to distinguish. To maximise the discrimination with the Pierre Auger Observatory ideally all mass-sensitive observables should be combined, but the 10% duty cycle of the fluorescence detector limits the use of direct measurements of shower maximum at the highest energies. Therefore, we investigate mass-sensitive observables accessible with the surface d…
This paper presents the highlights from the recent measurements of the energy spectrum, mass composition, and arrival directions of the ultra-high energy ($> 10^{17}$ eV = 0.1 EeV) cosmic rays (UHECR) by the Pierre Auger Observatory. The Auger hybrid detector combines fluorescence observations of the longitudinal profiles of extended air showers, initiated by these extremely energetic particles, with measures of the shower secondaries at the ground level by its large array of Cherenkov water tanks. The complementariness of the two techniques provides important cross-checks at the energies unre…
(abridged) The Pierre Auger Collaboration has reported 27 Ultra-High Energy Cosmic Ray Events (UHECRs) with energies above 56 EeV and well determined arrival directions as of 2007 August 31. They find that the arrival directions are not isotropic, but instead appear correlated with the positions of nearby AGNs. Our aim was to determine the sources of these UHECRs by comparing their arrival directions with more comprehensive source catalogs. Four (eight) of the 27 UHECRs with energy >56EeV detected by the Pierre Auger Observatory have arrival directions within 1.5deg (3.5deg) of the extended (>…
FRAM - F/(Ph)otometric Robotic Atmospheric Monitor is the latest addition to the atmospheric monitoring instruments of the Pierre Auger Observatory. An optical telescope equipped with CCD camera and photometer, it automatically observes a set of selected standard stars and a calibrated terrestrial source. Primarily, the wavelength dependence of the attenuation is derived and the comparison between its vertical values (for stars) and horizontal values (for the terrestrial source) is made. Further, the integral vertical aerosol optical depth can be obtained. A secondary program of the instrument…
We consider the scattering of the brane fields due to t-channel massive graviton exchanges in the Randall-Sundrum model. The eikonal amplitude is analytically calculated and both differential and total neutrino-nucleon cross sections are estimated. The event rate of quasi-horizontal air showers induced by cosmic neutrinos, which can be detected at the Pierre Auger Observatory, is presented for two different fluxes of cosmogenic neutrinos.
The Pierre Auger Observatory has been designed to study the highest-energy cosmic rays in nature (E > 10^{18.5} eV). The determination of their arrival direction, energy and composition is performed by the analysis of the atmospheric showers they produce. The Auger Surface Array will consist of 1600 water Cerenkov detectors placed in an equilateral triangular grid of 1.5 km spacing. The aim of this paper is to show that the addition of a "small" area of surface detectors at half or less the above mentioned spacing would allow a dramatic increase of the physical scope of this Observatory, reach…
Motivated by recent Pierre Auger result on the correlation of the highest-energy cosmic rays with the nearby active galactic nuclei, we explore possible ultrahigh energy cosmic ray (UHECR) source distributions and their effects on GZK horizons. Effects on GZK horizons by local over-density of UHECR sources are examined carefully with constraints on the degree of local over-density inferred from the measured UHECR spectrum. We include the energy calibration effect on the Pierre Auger data in our studies. We propose possible local over-densities of UHECR sources which are testable in the future …
Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surfa…
We calculate for the nearest active galactic nucleus (AGN), Centaurus A, the flux of high energy cosmic rays and of accompanying secondary photons and neutrinos expected from hadronic interactions in the source. We use as two basic models for the generation of ultrahigh energy cosmic rays (UHECR) shock acceleration in the radio jet and acceleration in the regular electromagnetic field close to the core of the AGN. While scattering on photons dominates in scenarios with acceleration close to the core, scattering on gas becomes more important if acceleration takes place along the jet. Normalizin…
The precise determination of the arrival direction of cosmic rays is a fundamental prerequisite for the search for sources or the study of their anisotropies on the sky. One of the most important aspects to achieve an optimal measurement of these directions is to properly take into account the measurement uncertainties in the estimation procedure. In this article we present a model for the uncertainties associated with the time measurements in the Auger surface detector array. We show that this model represents well the measurement uncertainties and therefore provides the basis for an optimal …
Neutrinos at energies ranging from sub-TeV to EeV from astrophysical sources can yield interesting physical information about fundamental interactions, about cosmic rays and about the nature of the sources and their environment. Gamma-ray bursts are a leading candidate source, and their expected neutrino emission can address a number of current questions, which may be answered with forthcoming experiments such as IceCube, Auger, ANITA and KM3NeT.
We construct the open-string scattering amplitudes for neutrino-gluon collisions and evaluate the high energy neutrino-nucleon scattering cross section via string state excitations in the TeV string-scale scenario. We find that the neutrino-gluon scattering is the dominant contribution, 5-10 times larger than neutrino-quark processes, though black hole production may be larger than the string contribution at higher energies. We illustrate the observability of the string signal at the Auger Observatory and the IceCube neutrino telescope for a string scale about 1 TeV.
The Randall-Sundrum model with a small curvature is considered in which five-dimensional Planck scale lies in the TeV region, and a spectrum of Kaluza-Klein gravitons reminds that in one flat extra dimension. The cross sections for interactions of ultra-high energy cosmic neutrinos with nucleons are calculated. It is shown that effects related with massive graviton excitations can be detected in deeply penetrating inclined air showers induced by these neutrinos. The expected number of air showers at the Auger Observatory is estimated as a function of two parameters of the model.
Air fluorescence detectors measure the energy of ultra-high energy cosmic rays by collecting fluorescence light emitted from nitrogen molecules along the extensive air shower cascade. To ensure a reliable energy determination, the light signal needs to be corrected for atmospheric effects, which not only attenuate the signal, but also produce a non-negligible background component due to scattered Cherenkov light and multiple-scattered light. The correction requires regular measurements of the aerosol attenuation length and the aerosol phase function, defined as the probability of light scatter…
If, as recently proposed by Farrar and Piran, Cen A is the source of cosmic rays detected above the Greisen-Zatsepin-Kuz'min cutoff, neutrons are $\approx 140$ more probable than protons to be observed along its line of sight. This is because the proton flux is rendered nearly isotropic by ${\cal O}(μ$G) intergalactic magnetic fields. With the anticipated aperture of the Southern Auger Observatory, one may expect on the order of 2 neutron events/year above $10^{20}$ eV in the line of sight of Cen A.
We deduce the cosmogenic neutrino flux by jointly analysing ultra high energy cosmic ray data from HiRes-I and II, AGASA and the Pierre Auger Observatory. We make two determinations of the neutrino flux by using a model-dependent method and a model-independent method. The former is well-known, and involves the use of a power-law injection spectrum. The latter is a regularized unfolding procedure. We then use neutrino flux bounds obtained by the RICE experiment to constrain the neutrino-nucleon inelastic cross section at energies inaccessible at colliders. The cross section bounds obtained usin…
In scenarios with extra dimensions and TeV-scale quantum gravity, black holes are expected to be produced copiously at center-of-mass energies above the fundamental Planck scale. The Large Hadron Collider (LHC) may thus turn into a factory of black holes, at which their production and evaporation may be studied in detail. But even before the LHC starts operating, the Pierre Auger Observatory for cosmic rays, presently under construction, has an opportunity to search for black hole signatures. Black hole production in the scattering of ultrahigh energy cosmic neutrinos on nucleons in the atmosp…
We elucidate the physical basis for the upper bound on high energy neutrino fluxes implied by the observed cosmic ray flux. We stress that the bound is valid for neutrinos produced either by p,gamma reactions or by p-p(n) reactions in sources which are optically thin for high energy protons to photo-meson and nucleon-meson interactions. We show that the upper bound is robust and conservative. The Waxman-Bahcall bound overestimates the most likely neutrino flux by a factor ~ 5/tau, for small optical depths tau. The upper limit cannot be plausibly evaded by invoking magnetic fields, optically th…
The next generation of neutrino and gamma-ray detectors should provide new insights into the creation and propagation of high-energy protons within galaxy clusters, probing both the particle physics of cosmic rays interacting with the background medium and the mechanisms for high-energy particle production within the cluster. In this paper we examine the possible detection of gamma-rays (via the GLAST satellite) and neutrinos (via the ICECUBE and Auger experiments) from the Coma cluster of galaxies, as well as for the gamma-ray bright clusters Abell 85, 1758, and 1914. These three were selecte…
A new air-showering physics may rise in next years at horizon, offering at different angles and altitudes a fine tuned filtered Cosmic Rays astrophysics and an upward Neutrino induced air-showering astronomy. Most of this opportunity arises because of neutrino masses, their mixing and the consequent replenishment of rarest tau flavor during its flight in Space. Horizontal air atmosphere act as a filter for High energy Cosmic Rays (CR) and as a beam dump for Ultra High Energy (UHE) neutrinos and a powerfull amplifier for its tau decay in air by its wide showering areas. Earth sharp shadows play…
