Cosmic Ray in the Northern Hemisphere: Results from the Telescope Array Experiment

The Telescope Array (TA) is the largest ultrahigh energy (UHE) cosmic ray observatory in the northern hemisphere TA is a hybrid experiment with a unique combination of fluorescence detectors and a stand-alone surface array of scintillation counters. We will present the spectrum measured by the surface array alone, along with those measured by the fluorescence detectors in monocular, hybrid, and stereo mode. The composition results from stereo TA data will be discussed. Our report will also include results from the search for correlations between the pointing directions of cosmic rays, seen by the TA surface array, with active galactic nuclei.Comment: 8 pages 11 figure, Proceedings of the APS Division of Particle and Fields (DPF) Meeting, Aug 2011, Brown University, Providence, RI, US

BL Lacertae are probable sources of the observed ultra-high energy cosmic rays

We calculate angular correlation function between ultra-high energy cosmic rays (UHECR) observed by Yakutsk and AGASA experiments, and most powerful BL Lacertae objects. We find significant correlations which correspond to the probability of statistical fluctuation less than $10^{-4}$, including penatly for selecting the subset of brightest BL Lacs. We conclude that some of BL Lacs are sources of the observed UHECR and present a list of most probable candidates.Comment: Replaced with the version accepted for publication in JETP Let

UHE nuclei propagation and the interpretation of the ankle in the cosmic-ray spectrum

We consider the stochastic propagation of high-energy protons and nuclei in the cosmological microwave and infrared backgrounds, using revised photonuclear cross-sections and following primary and secondary nuclei in the full 2D nuclear chart. We confirm earlier results showing that the high-energy data can be fit with a pure proton extragalactic cosmic ray (EGCR) component if the source spectrum is \propto E^{-2.6}. In this case the ankle in the CR spectrum may be interpreted as a pair-production dip associated with the propagation. We show that when heavier nuclei are included in the source with a composition similar to that of Galactic cosmic-rays (GCRs), the pair-production dip is not present unless the proton fraction is higher than 85%. In the mixed composition case, the ankle recovers the past interpretation as the transition from GCRs to EGCRs and the highest energy data can be explained by a harder source spectrum \propto E^{-2.2} - E^{-2.3}, reminiscent of relativistic shock acceleration predictions, and in good agreement with the GCR data at low-energy and holistic scenarios.Comment: 4 pages, 4 figures, submitted to A&A Letters (minor changes, two figures replaced, two references added

Galactic Anisotropy as Signature of ``Top-Down'' Mechanisms of Ultra-High Energy Cosmic Rays

We show that ``top-down'' mechanisms of Ultra-High Energy Cosmic Rays which involve heavy relic particle-like objects predict Galactic anisotropy of highest energy cosmic rays at the level of minimum $\sim 20$. This anisotropy is large enough to be either observed or ruled out in the next generation of experiments.Comment: 8 pages, 1 figure, LaTeX. Final version appeared in Pisma Zh. Eksp. Teor. Fi

Representations of spectral coordinates in FITS

Greisen & Calabretta describe a generalized method for specifying the coordinates of FITS data samples. Following that general method, Calabretta & Greisen describe detailed conventions for defining celestial coordinates as they are projected onto a two-dimensional plane. The present paper extends the discussion to the spectral coordinates of wavelength, frequency, and velocity. World coordinate functions are defined for spectral axes sampled linearly in wavelength, frequency, or velocity, linearly in the logarithm of wavelength or frequency, as projected by ideal dispersing elements, and as specified by a lookup table.Comment: 25 pages, 5 figure

Possible Signature of Low Scale Gravity in Ultra High Enegry Cosmic Rays

We show that the existence of low scale gravity at TeV scale could lead to a direct production of photons with energies above 10^22 eV due to annihilation of ultra high energy neutrinos on relic massive neutrinos of the galactic halo. Air showers initialized in the terrestrial atmosphere by these ultra energetic photons could be collected in near future by the new generation of cosmic ray experiments.Comment: 5 pages, 3 figure

Ultra-High Energy Cosmic Rays and Stable H-dibaryon

It is shown that an instanton induced interaction between quarks produces a very deeply bound H-dibaryon with mass below 2M_N, M_H=1718 MeV. Therefore the H-dibaryon is predicted to be a stable particle. The reaction of photodisintegration of H-dibaryon to $2\Lambda$ in during of its penetration into cosmic microwave background will result in a new possible cut-off in the cosmic-ray spectrum. This provides an explanation of ultra-high energy cosmic ray events observed above the GZK cut-off as a result of the strong interaction of high energy H-dibaryons from cosmic rays with nuclei in Earth's atmosphere.Comment: 5 pages, Late

Generation of 10^15 - 10^17 eV photons by UHE CR in the Galactic magnetic filed

We show that the deep expected in the diffuse photon spectrum above the threshold of e+e- pair production, i.e., at energies 10^15 - 10^17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magnetic filed. The mechanism we propose requires small (less than 2x10^-12 G) extragalactic magnetic fields and large fraction of photons in the UHE CR. For a typical photon flux expected in top-down scenarios of UHE CR, the predicted flux in the region of the deep is close to the existing experimental limit. The sensitivity of our mechanism to the extragalactic magnetic field may be used to improve existing bounds on the latter by two orders of magnitude.Comment: 11 pages, LaTeX, 1 .ps figure. Numerical error corrected; references adde

trans-GZK Cosmic Rays: Strings, Black Holes, Neutrinos, or All Three?

We review the scenario in which ``strongly interacting neutrinos'' are responsible for inducing airshowers with inferred energies $E > 8\times10^{19}$ eV. This possibility arises naturally in string excitation models having a unification scale effectively decoupled from the Planck scale. We then show that phenomenological quantum gravity considerations reveal an equivalency of ``mini-black hole'' and strongly interacting neutrino pictures for explaining trans-GZK events. This equivalence can be exploited to predict single particle inclusive distributions. The resulting observable consequences in airshower development are studied using the Adaptive Longitudinal Profile Shower (ALPS) simulation.Comment: Talk presented at Cosmic Ray International Seminar (CRIS), Catania, Sicily, 2004; 6 pages, 6 figure