The High Energy Stereoscopic System (HESS) international collaboration has published the results of 15 years of very high energy gamma ray observations of the Milky Way.
The collaboration has studied populations of pulsar nebulae, remnants of supernovae, as well as micro-quasars, never detected in gamma rays.
The studies are accompanied by precise measurements such as the diffuse emission at the centre of our galaxy. This data will now be used as a reference for the international science community.
Published in the journal Astronomy & Astrophysics, the 14 articles are the largest set of scientific results in this field.
Emission of gamma rays
In the Universe, cosmic particles are accelerated by clusters of galaxies, supernovae, double stars, pulsars or some types of supermassive black holes. Through a mechanism that is not yet fully understood, they acquire a very high energy which is made visible by the emission of gamma rays.
When these gamma rays reach the Earth’s atmosphere, they are absorbed and produce secondary particles that emit faint flashes of light, known as ‘Cherenkov light’, in just a few billionths of a second.
The new release of the HESS Galactic Plane Survey catalogue is larger than the previous one and is the first-time gamma data set to be published.
HESS has also revealed the particle accelerators underlying these gamma sources and how cosmic rays are moving in the interstellar medium and shaping their environment. Finally, HESS has also detected emissions from new classes of objects emitting gamma rays of very high energy, such as black holes or stellar mass orbiting around massive stars, and has characterised the absence of emission of other classes of objects.
HESS’s record is so significant that it shows that gamma astronomy at very high energies has reached maturity.
The HESS collaboration has already been awarded the European Commission Descartes Prize in 2006, and the Rossi Prize of the American Astronomical Society (AAS) in 2010. Today’s HESS results will serve the Cherenkov Telescope Array’s (CTA) observational strategy and remain the gold standard in gamma-ray astronomy.