2 research outputs found
Small Scale Anisotropy Predictions for the Auger Observatory
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, Mpc, with between 3 and 6.
These densities span a wide range of extragalactic sites for UHECR sources,
from common to rare galaxies or even clusters of galaxies. We simulate 100
realizations for each model and calculate the two point correlation function
for events with energies above 4 \times 10^{19}\eV and above 10^{20}\eV, as
specialized to the case of the Auger telescope. We find that for r\ga 4,
Auger should be able to detect small scale anisotropies in the near future.
Distinguishing between different source densities based on cosmic ray data
alone will be more challenging than detecting a departure from isotropy and is
likely to require larger statistics of events. Combining the angular
distribution studies with the spectral shape around the GZK feature will also
help distinguish between different source scenarios.Comment: 15 pages, 6 figures, 6 tables, submitted to JCA
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, 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