More than hot: Sources of cosmic gamma rays
Research report (imported) 2004 - Max Planck Institute for extraterrestrial Physics
The INTEGRAL Gamma-Ray Observatory has provided novel insight into the nature of sources of high-energy radiation. New embedded sources were discovered, because only the high-energy part of radiation can penetrate clouds. Unexpected emission at high energies where thermal emission usually fades was found for sources with extremely high magnetic fields. Together, this leads to a re-evaluation of the relative contributions of source objects and intrinsically-diffuse emission from interstellar space. Such diffuse emission reflects cosmic radiation penetrating the interstellar gas in the Galaxy. High-resolution spectroscopy of diffuse emission addresses mainly two prominent gamma-ray lines: Antimatter annihilates into electromagnetic radiation with a line at 511 keV, and was found to have a surprisingly symmetric spatial distribution in the inner Galaxy; radiactive 26Al decays in the interstellar medium of the Galaxy, emitting a line at 1809 keV; being a by-product of cosmic element synthesis from terminal evolutionary phases of very massive stars, it was ejected into interstellar space, and thus reveals the kinematics of the interstellar gas in such regions, which are hardly accessible through other means.