The Federal Minister for Education and Research, Annette Schavan, awarded the one million euro prize on Wednesday, together with the EU's Science and Research Commissioner, Janez Potocnik. The award ceremony took place in Brussels at the start of the 7th European Framework Program entitled "Today is future". The H.E.S.S team shares the Descartes Prize with two other international research projects. The European Commission's Descartes Prize is named after the French philosopher and mathematician, Rene Descartes (1596 - 1650) and was awarded for the first time in 2000. The research prize honours scientific teams that have achieved outstanding scientific and technological results in trans-national projects.
The H.E.S.S. team was among the ten finalists in 2006 - however, this year they made it all the way to the winner's podium. The H.E.S.S. project's success story is certainly impressive: fully functional since 2004, the detectors have literally opened up a new window on outer space for scientists. The H.E.S.S. telescopes, with their wide field of vision - equivalent to ten times the surface of the moon - are ideal for discovering new sources of cosmic gamma rays. In just a few months, scientific findings from H.E.S.S. observations have resulted in more than 30 publications in scientific journals, including numerous reports in prominent journals like Nature and Science.
Here is a selection of the key findings:
- With some of their very first measurements, scientists managed to record the first astronomic image of a supernova shock wave with ultra-high energies. In the process, H.E.S.S. identified, for the first time, the explosion clouds of supernovae as a source of high-energy cosmic rays - in other words, gigantic cosmic particle accelerators.
- Within a few months, H.E.S.S. had already found eight new sources of high-energy gamma rays at the centre of the Milky Way - almost doubling the number of known sources to that date.
- H.E.S.S. experiments proved that high-energy cosmic rays at the centre of the Milky Way are more intense than they are in the vicinity of Earth. A possible explanation for this phenomenon could be either a prior supernova or a case of massive particle acceleration by the super-massive black hole at our galaxy’s centre.
- In October 2006, H.E.S.S. scientists reported the discovery of fast changing, very high-energy gamma radiation from the giant radio galaxy M 87. So far, this is the only radio galaxy that has been proven to emit gamma radiation with energies a trillion times higher that those of visible light.
- In late 2006, the H.E.S.S. telescope was the first ever to identify a regularly pulsing source of gamma radiation in the Milky Way. Previous observations had been limited to 100,000 times smaller energies. The radiation originates from a double-star system with the catalogue name LS 5039, in which a compact body (a neutron star or a black hole) races around a giant blue star on an eccentric orbit in just four days.
All of these discoveries are made possible by a system consisting of four telescopes. H.E.S.S. was constructed by an international team of more than 100 scientists and engineers from Germany, France, England, Ireland, the Czech Republic, Armenia, South Africa and Namibia between 2001 and 2003. The system was officially put into operation in September 2004. With a diameter of 13 meters each, the H.E.S.S. telescopes are the most sensitive measuring instruments available to date for high-energy gamma rays, which are very difficult to detect; even a strong source emits only one radiation quant per month, per square meter into our atmosphere, where it is absorbed. Detecting them directly would therefore require an enormous satellite instrument.
Consequently, the H.E.S.S. telescopes employ a cunning trick: they use the atmosphere as a detection medium. When gamma quants are absorbed, they emit short pulses of what is known as Cherenkov light - a blue light lasting for no more than a few billionths of a second. This light is captured by the H.E.S.S. telescopes' huge mirrors and sensitive photosensors. The scientists then use the data to generate images of astronomical objects in the "light" of high-energy gamma rays.
Outer space surely still has many surprises in store for the H.E.S.S. scientists. The researchers reported their latest discovery a few short weeks ago: a new type of gamma emitter. For the very first time, they were able to assign high-energy gamma rays to a Wolf-Rayet star - a high-mass star at the end of its life, but before its "death" as a supernova.