Global anisotropy of arrival directions of ultra-high-energy cosmic rays: capabilities of space-based detectors

Planned space-based ultra-high-energy cosmic-ray detectors (TUS, JEM-EUSO and S-EUSO) are best suited for searches of global anisotropies in the distribution of arrival directions of cosmic-ray particles because they will be able to observe the full sky with a single instrument. We calculate quantitatively the strength of anisotropies associated with two models of the origin of the highest-energy particles: the extragalactic model (sources follow the distribution of galaxies in the Universe) and the superheavy dark-matter model (sources follow the distribution of dark matter in the Galactic halo). Based on the expected exposure of the experiments, we estimate the optimal strategy for efficient search of these effects.Comment: 19 pages, 7 figures, iopart style. v.2: discussion of the effect of the cosmic magnetic fields added; other minor changes. Simulated UHECR skymaps available at http://livni.inr.ac.ru/UHECRskymaps