A model is proposed for the origin of cosmic rays (CRs) from ∼ 10 14 eV/nucleon to the highest energies ( > ∼ 10 20 eV). GRBs are assumed to inject CR protons and ions into the interstellar medium of star-forming galaxies-including the Milky Waywith a power-law spectrum extending to a maximum energy ∼ 10 20 eV. The CR spectrum near the knee is fit with CRs trapped in the Galactic halo that were accelerated and injected by an earlier Galactic GRB. These CRs diffuse in the disk and halo of the Galaxy due to gyroresonant pitch-angle scattering with MHD turbulence in the Galaxy's magnetic field. The preliminary (2001) KASCADE data through the knee of the CR spectrum are fit by a model with energy-dependent propagation of CR ions from a single Galactic GRB. Ultra-high energy CRs (UHECRs), with energies above the ankle energy at > ∼ 3 × 10 18 eV, are assumed to propagate rectilinearly with their spectrum modified by photo-pion, photo-pair, and expansion losses. We fit the measured UHECR spectrum assuming comoving luminosity densities of GRB sources consistent with possible star formation rate histories of the universe.For power-law CR proton injection spectra with injection number index p > ∼ 2 and low and high-energy cutoffs, normalization to the local time-and space-averaged GRB luminosity density implies that if this model is correct, the nonthermal content in GRB blast waves is hadronically dominated by a factor ≈ 60-200, limited in its upper value by energetic and spectral considerations. Calculations show that 100 TeV -100 PeV neutrinos could be detected several times per year from all GRBs with kilometer-scale neutrino detectors such as IceCube, for GRB blast-wave Doppler factors δ < ∼ 200. GLAST measurements of γ-ray components and cutoffs will constrain the product of the nonthermal baryon loading and radiative efficiency, limit the Doppler factor, and test this scenario.

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We calculate the diurnal and annual modulation of the signals in axion and WIMP dark matter detectors on Earth caused by a cold flow of dark matter in the Solar neighborhood. The effects of the Sun's and the Earth's gravity, and of the orbital and rotational motions of the Earth are included. A cold flow on Earth produces a peak in the spectrum of microwave photons in cavity detectors of dark matter axions, and a plateau in the nuclear recoil energy spectrum in WIMP detectors. Formulas are given for the positions and heights of these peaks and plateaux as a function of time in the course of day and year, including all corrections down to the 0.1% level of precision. The results can be applied to an arbitrary dark matter velocity distribution f ( v) by integrating the one-flow results over velocities. We apply them to the set of flows predicted by the caustic ring model of the Galactic halo. The caustic ring model predicts the dark matter flux on Earth to be largest in December ± one month. Nonetheless, because of the role of energy thresholds, the model is consistent with the annual modulation results published by the DAMA collaboration provided the WIMP mass is larger than approximately 100 GeV.

We analyze the effect of the Sun's gravitational field on a flow of cold dark matter (CDM) through the solar system in the limit where the velocity dispersion of the flow vanishes. The exact density and velocity distributions are derived in the case where the Sun is a point mass. The results are extended to the more realistic case where the Sun has a finite size spherically symmetric mass distribution. We find that regions of infinite density, called caustics, appear. One such region is a line caustic on the axis of symmetry, downstream from the Sun, where the flow trajectories cross. Another is a cone-shaped caustic surface near the trajectories of maximum scattering angle. The trajectories forming the conical caustic pass through the Sun's interior and probe the solar mass distribution, raising the possibility that the solar mass distribution may some day be measured by a dark matter detector on Earth. We generalize our results to the case of flows with continuous velocity distributions, such as that predicted by the isothermal model of the Milky Way halo.PACS number: 98.80 Cq 1