JEM-EUSO scientific objectives

International audienceJEM-EUSO is a space telescope to be installed at the International Space Station to observe extensive air showers (EAS) in the Earths atmosphere produced by cosmic rays of energies above 50 EeV. JEM-EUSO will reach the unprecedented annual exposure at the highest energies of more than 6×104 km2 sr yr with very nearly uniform dependence on declination over the Celestial Sphere. These capabilities go far beyond what can be practically achieved by ground-based observatories and enable an all sky study of anisotropies above 60 EeV where hints of anisotropies have been reported. The decrease in attenuation length of UHECRs with increasing energy implies that the extreme energy cosmic ray sky must be dominated by very few, relatively nearby sources. The full sky analysis of JEM-EUSO anisotropy patterns should unveil the closest of these extreme sources of the highest energy particles ever observed. These anisotropy patterns as a function of energy can also set constraints on the particle charge and the effects of Galactic and extragalactic magnetic fields. The higher statistics measurement of the spectrum at extreme energies (above 100 EeV) can test if the maximum energy of these extreme accelerators reaches well beyond the GZK feature or if it coincides with the GZK effect further constraining the source characteristics. JEM-EUSO will also study transient light events in the atmosphere related to meteors and atmospheric phenomena. In addition, JEM-EUSO will set limits on Lorenz Invariance violation and will search for nucleates and extreme energy photons and neutrinos that could lead to ground-breaking discoveries in fundamental physics