UHECRs have attracted a lot of attention due to their challengingly highenergies and their potential value to constrain physical processes andastrophysical parameters in the most energetic sources of the universe. Currentdetectors have failed to detect significant anisotropies which had beenexpected to allow source identification. Some indications about the UHECRcomposition, which may become heavier at the highest energies, has even putinto question the possibility that such a goal could be achieved soon. We investigate the potential value of a new-generation detector, with 10times larger exposure, to overcome the current situation and make significantprogress in the detection of anisotropies and thus in the study of UHECRs. Wetake as an example the expected performances of the JEM-EUSO, assuming auniform full-sky coverage with a total exposure of 300,000 km2 sr yr. We simulate realistic UHECR sky maps for a wide range of possibleastrophysical scenarios allowed by the current constraints, taking into accountthe energy losses and photo-dissociation of the UHECRs, as well as theirdeflections by magnetic fields. These sky maps, built for the expectedstatistics of JEM-EUSO as well as for the current Auger statistics, as areference, are analyzed from the point of view of their intrinsic anisotropies,using the two-point correlation function. A statistical study of the resultinganisotropies is performed for each astrophysical scenario, varying the UHECRsource composition and spectrum as well as the source density. We find that significant anisotropies are expected to be detected by anext-generation UHECR detector, for essentially all the astrophysical scenariosstudied, and give precise, quantitative meaning to this statement. Our resultsshow that a gain of one order of magnitude in exposure would make a significantdifference compared to the existing detectors.
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