Light Nuclei solving Auger puzzles. The Cen-A imprint

Ultra High Energy Cosmic Rays (UHECR) map at 60 EeV have been found recently by AUGER group spreading anisotropy signatures in the sky. The result have been interpreted as a manifestation of AGN sources ejecting protons at GZK edges mostly from Super-galactic Plane. The result is surprising due to the absence of much nearer Virgo cluster. Moreover, early GZK cut off in the spectra may be better reconcile with light nuclei (than with protons). In addition a large group (nearly a dozen) of events cluster suspiciously along Cen-A. Finally, proton UHECR composition nature is in sharp disagreement with earlier AUGER claim of a heavy nuclei dominance at 40 EeV. Therefore we interpret here the signals as mostly UHECR light nuclei (He, Be, B, C, O), very possibly mostly the lightest (He,Be) ones, ejected from nearest AGN Cen-A, UHECR smeared by galactic magnetic fields, whose random vertical bending is overlapping with super-galactic arm. The eventual AUGER misunderstanding took place because of such a rare coincidence between the Super Galactic Plane (arm) and the smeared (randomized) signals from Cen-A, bent orthogonally to the Galactic fields. Our derivation verify the consistence of the random smearing angles for He, Be and B, C, O, in reasonable agreement with the AUGER main group events around Cen-A. Only few other rare events are spread elsewhere. The most collimated from Cen-A are the lightest. The most spread the heavier. Consequently Cen-A is the best candidate UHE neutrino tau observable by HEAT and AMIGA as enhanced AUGER array at tens-hundred PeV energy. This model maybe soon tested by new events clustering around the Cen-A and by composition imprint study.Comment: 4 pages, 5 figures

Ultra-High Energy Cosmic Ray production in the polar cap regions of black hole magnetospheres

We develop a model of ultra-high energy cosmic ray (UHECR) production via acceleration in a rotation-induced electric field in vacuum gaps in the magnetospheres of supermassive black holes (BH). We show that if the poloidal magnetic field near the BH horizon is misaligned with the BH rotation axis, charged particles, which initially spiral into the BH hole along the equatorial plane, penetrate into the regions above the BH "polar caps" and are ejected with high energies to infinity. We show that in such a model acceleration of protons near a BH of typical mass 3e8 solar masses is possible only if the magnetic field is almost aligned with the BH rotation axis. We find that the power of anisotropic electromagnetic emission from an UHECR source near a supermassive BH should be at least 10-100 times larger then UHECR power of the source. This implies that if the number of UHECR sources within the 100 Mpc sphere is ~100, the power of electromagnetic emission which accompanies proton acceleration in each source, $10^{42-43}$ erg/s, is comparable to the typical luminosities of active galactic nuclei (AGN) in the local Universe. We also explore the acceleration of heavy nuclei, for which the constraints on the electromagnetic luminosity and on the alignment of magnetic field in the gap are relaxed

Implications of the cosmic ray spectrum for the mass composition at the highest energies

The significant attenuation of the cosmic-ray flux above $\sim 5 10^{19}$ eV suggests that the observed high-energy spectrum is shaped by the so-called GZK effect. This interaction of ultra-high-energy cosmic rays (UHECRs) with the ambient radiation fields also affects their composition. We review the effect of photo-dissociation interactions on different nuclear species and analyze the phenomenology of secondary proton production as a function of energy. We show that, by itself, the UHECR spectrum does not constrain the cosmic-ray composition at their extragalactic sources. While the propagated composition (i.e., as observed at Earth) cannot contain significant amounts of intermediate mass nuclei (say between He and Si), whatever the source composition, and while it is vastly proton-dominated when protons are able to reach energies above $10^{20}$ eV at the source, we show that the propagated composition can be dominated by Fe and sub-Fe nuclei at the highest energies, either if the sources are very strongly enriched in Fe nuclei (a rather improbable situation), or if the accelerated protons have a maximum energy of a few $10^{19}$ eV at the sources. We also show that in the latter cases, the expected flux above $3 10^{20}$ eV is very much reduced compared to the case when protons dominate in this energy range, both at the sources and at Earth.Comment: 16 pages, 7 figure

Foreground contributions to the cosmic microwave background

A detailed search has been made for evidence of residual foreground contributions to the cosmic microwave background (CMB) in the map generated by the Wilkinson Microwave Anisotropy Probe (WMAP), a map that has been (nominally) cleaned for the foreground already. We find positive results in that various features relate to Galactic properties. For example, on the largest angular scales we find significant differences between the power in the fluctuations for positive and negative Galactic latitudes and between the four Galactic quadrants. There are also differences between the power spectrum at latitudes within 10 degrees of the plane and at higher latitudes. The mean temperature shows similar variations. An explanation in terms of Galactic effects seems inescapable. In an effort to find the origin of these Galactic-style effects we have examined evidence from Galactic gamma-rays, specifically from the EGRET instrument. We are mindful that the CMB maps examined have already been 'cleaned' (for CR and other effects) in a rather complex way, but, in our view, the cleaning has left some potentially serious 'contaminations'. A correlation is found between gamma-ray intensities and the CMB and other CR indicators. For example, regions of the Galaxy having (line-of-sight) steep CR energy spectra have low mean CMB temperatures, and the important Loop I edge region, where the CR intensity is high, has a high mean temperature. Most of the large-scale Galactic asymmetries (e.g. north-south difference and quadrant variations) have analogues in CR asymmetries and also in some other Galactic properties, such as the column density of gas. Thus, it is possible to hypothesize about direct CR-induced contributions, although it may be that CRs are simply the indicators of Galactic 'conditions' which are influencing the residual CMB fluctuations. Irrespective of the actual cause of the correlations we have endeavoured to extrapolate to the situation where the residual foreground is minimized. The effect on the usually derived cosmological properties is briefly examined. The least that can be said is that the 'error' in some of these properties has been underestimated