eROSITA X-ray telescope launch

The Russian-German mission will provide the first complete sky survey in the medium X-ray range. eROSITA will study the distribution of huge galaxy clusters and find out more about the mysterious dark energy that influences their formation and evolution. It is expected to detect about 100,000 clusters of galaxies, the largest gravitationally bound objects, which map the large-scale structure of the universe and provide insights into how it is expanding. An estimated three million active galactic nuclei (AGN) containing massive black holes will be discovered. Within our Milky Way, eROSITA will discover about 700,000 active stars and 10,000 compact objects including binary stars and stellar explosions such as supernovae and their remnants.

eROSITA (extended Roentgen Survey with an Imaging Telescope Array) is an X-ray telescope built by a German consortium under the leadership of theMax Planck Institute for Extraterrestrial Physicsin Garching. The Leibniz Institute for Astrophysics Potsdam (AIP) contributed to the data reduction software system with special emphasis on the attitude solution system and the source detection. AIP also provided flight hardware for the camera filter wheels and the whole mechanical ground segment equipment for integration and tests of the X-ray telescope array.

"We have come a long way. Behind us lie 12 years of preparation with ups and downs. A real highlight is right ahead of us and, naturally, we feel a growing tension whether everything will work out,” says Axel Schwope, eROSITA project leader at AIP. “Our position-determining software will be called into action a few days after the launch and after all the tests its components will soon have to prove their suitability in space. We are proud that eROSITA, the main instrument aboard SRG (Spectrum X-Ray Gamma), has been assembled in the integration and test rig we delivered." Prof. Matthias Steinmetz, scientific director of the AIP, emphasizes that "a few parts Made-in-Potsdam, holders of the calibration sources in the 7 filter wheels, are also onboard."

The approved mission time is seven years. During the first four years of the mission, eight independent all-sky X-ray surveys will be performed. An operational phase with pointed observations will follow and last for 2.5 years. “The X-ray images and the catalogues – the basis for a scientific evaluation – will be created with our software. The first data which is specifically for us at the AIP will be recorded in October and we will virtually leap at it,” adds project scientist Dr. Georg Lamer. “After six months, eROSITA will have found more sources of X-ray radiation in the sky than in the first 50 years of X-ray astronomy. For now, we will celebrate these great prospects.”

Members of AIP are also participating in the eROSITA scientific working groups. Optical identification of new X-ray sources is of major relevance: The eROSITA cluster and AGN surveys were selected as design reference surveys for the future 4MOST facility, a 4-meter multi-object spectroscopic telescope for the European Southern Observatory ESO, currently under construction lead by the AIP.