Unravelling the mysteries of cosmic rays
About a century ago, Austrian physicist Victor Hess discovered cosmic rays. Today, the origin of these rays is still unclear. Gamma radiation is one way of studying cosmic rays, but has not proven to be very reliable. The EU-funded project 'Sources of cosmic rays and gamma ray emission from the Galaxy' (DiffuseGammaEmission) studied gamma rays from each direction of the Galaxy. It compared their properties with data on the interstellar medium (ISM), i.e. the matter between star systems. The results were then used to examine cosmic ray flux in certain parts of the galaxy where traditional methods of examination weren't very fruitful. The project's main objective was to study sources and distribution of cosmic rays by comparing new, detailed gamma ray maps. Team members considered regions of high gas density or molecular clouds (MCs) and supernova remnants (SNRs), recording the multi wavelength spectrum from radio to gamma rays emerging from MCs. It found that some unidentified energy sources may in fact be associated with clouds illuminated by cosmic rays coming from a nearby source. Exploiting gas data from the surveys of molecular and atomic hydrogen in the galaxy, the project team examined spectral and spatial distributions of the emissions. Different predictions and results from the project are promising to revolutionise the way scientists understand cosmic rays and reveal a better picture of their idiosyncrasies and sources. Finally, a better picture of cosmic rays will emerge.
