‘research_tv’ presents LOFAR: the largest radio telescope in the world
What did the universe look like just after the Big Bang? How did the first stars and galaxies evolve? Seeking answers to these questions, researchers at Bielefeld University are looking way back into the past. With the digital radio telescope LOFAR, they are picking up signals that have taken billions of years to reach us. ‘research_tv’ is presenting the LOFAR station in Norderstedt. It is being run by Bielefeld University in cooperation with Universität Hamburg.
‘With this radio telescope, we can obtain very large and precise charts of galaxies. We can use these data to draw conclusions on how the universe developed,’ says Professor Dr. Dominik Schwarz from Bielefeld University’s Faculty of Physics. The astrophysicist and his research team are studying how structures evolve in the universe. He planned the LOFAR station in Norderstedt together with Professor Dr. Marcus Brüggen from the Sternwarte in Hamburg [Hamburg observatory] and his team, and it was inaugurated as the sixth LOFAR site in Germany in September 2015. LOFAR is made up of a total of 49 antenna fields spread throughout Europe. Such a wide dissemination permits a far higher resolution than that possible at one single location. This is why partners from Germany, the Netherlands, Poland, Great Britain, France, Sweden, and Ireland have joined together to build the largest radio telescope in the world.
In Norderstedt, the LOFAR station covers roughly the area of a football pitch. Second for second, 192 antenna assemblies are picking up radio waves from space. Each signal is given a precise time stamp so that it can flow together with the signals from the other LOFAR stations to form a total picture. ‘We know precisely down to ten nanoseconds when the signals reach here,’ according to Schwarz. The stations are synchronized over GPS and the signal is sent to Groningen in the Netherlands via the Forschungszentrum Jülich. Groningen is the location of LOFAR’s supercomputer that transforms the data into images.
Instead of capturing waves of visible light, LOFAR measures radio waves. ‘Shortly after the Big Bang, before there was structure or a star, the universe consisted of only neutral hydrogen. There was no light, and that is why this epoch is also called the dark ages of the universe,’ explains Professor Dr. Marcus Brüggen. ‘The only radiation was weak and came from neutral hydrogen. This radiation reaches us in exactly the frequency range in which we are carrying out our measurements.’ This frequency range is very low, between 10 and 240 megahertz, and has hardly been explored before. LOFAR stands for Low Frequency Array.
According to Professor Dr. Martin Egelhaaf, the Vice-Rector for Research, the LOFAR project is of great significance for both physics and Bielefeld University. ‘It makes an important contribution to internationalizing our university because we are cooperating not only with strong national partners such as Universität Hamburg or the Max Planck Society but also with a very strong partner in the Netherlands.’ On the German side, Bielefeld University and Universität Hamburg are joined by, for example, the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, the Max Planck Institute for Astrophysics (MPA) in Garching, and further universities and observatories. In the Netherlands, ASTRON, the Netherlands Institute for Radio Astronomy, is responsible for the project along with the Universities of Amsterdam, Groningen, Leiden, and Nijmegen.