Radio astronomical measurements allow the study of a variety of questions in fundamental physics. Those questions range from the equation-of-state of super-dense matter to the investigation of fundamental forces such as gravity and magnetism. In particular, the research group searches for and exploits fast-rotating neutrons stars that are visible as radio pulsars. Their observations allow us to test general relativity and alternative theories of gravity and works towards the detection of a long-wave cosmological gravitational wave background. Further studies exploit the information that is imprinted in radio emission about cosmic magnetic fields. Pulsars are used to study the magnetic milky way, while far-distant, external galaxies allow us to study cosmic magnetism. Magnetic fields are also important during the formation and the evolution of neutron stars.
The research team uses the millimetre- and sub-millimetre range of the electromagnetic spectrum to observe various phenomena in the universe. The cosmic background radiation is also being investigated, as well as molecular clouds in the Milky Way and other galaxies. Further research is being conducted on stellar evolution, radio emission of stars and the radiation of circumstellar molecular envelopes (radiation of stellar accretion disks), the late stages of stellar evolution, as well as the galactic centre. The research team has led the construction of the sub-millimetre telescope APEX in Chile. APEX was officially inaugurated on September 26th 2005 and has entered the phase of regular science operation. Together with international partners, it is also involved in the planning and construction of ALMA, a giant instrument consisting of an array of 64 separate telescopes, which is also to be constructed in Chile.
By employing radio-interferometry, extragalactic objects and their centres are investigated in great detail. The Very Long Base Line Interferometry (VLBI) method is applied by correlating data from telescopes distributed worldwide and using them as a "giant" combined telescope within the framework of coordinated arrays as the the European VLBI network (EVN). In addition, global VLBI experiments are conducted in cooperation with telescopes in the USA. The main area of scientific research is the centres of active galactic nuclei and their jets. One aim is to depict the shell of so-called "central engines" in active galactic centres, which are thought to coincide with "super-massive black holes".