AP4 - Thermal Behavior of Compact Stars |
Speaker_ |
Muller, Dietrich |
Talk _ |
Direct Observations of Cosmic Rays on Satellites and Balloons: Experimental Clues on their Origin and Interactions in the Galaxy |
Abstract _ |
Cosmic-ray energies span an enormous range, from the MeV region to almost incomprehensible values beyond 10^20 eV. To decipher the astrophysical or cosmological message of these particles, comprehensive measurements of their composition and energy spectra are needed but become progressively difficult as energy increases. At low energy, below about 10^10 eV, satellite data of very high precision are available on the elemental and even the isotopic composition of cosmic-ray nuclei. Up to about 5x1010 eV, the rare antiparticles antiproton and positron could be separated from protons and electrons, respectively. Up to much higher energies, close to 10^15 eV , direct measurements on balloon or in space may determine the nuclear charge Z and the energy or rigidity of cosmic-ray nuclei. Such detail cannot yet be derived from the indirect measurements through air shower observations which must be used at still higher energies. In this paper, we will concentrate on the range of direct measurements. The resulting data provide, together with other astronomic information, the basis for answering key questions such as the origin of the cosmic-ray material, the acceleration process, interactions of cosmic rays in the interstellar medium, and possible contributions of exotic particles (e.g., dark matter candidates) to the cosmic-ray intensity. We will review the currently available constraints on theoretical models, and we shall discuss how future progress may be achieved. |