Universiteit Leiden

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From Big Bang to algorithm

Smart algorithms and powerful processors are just as essential for astronomy as big telescopes. Astronomers at Leiden University therefore constantly operate at the interface between astronomy and data science.

What happened immediately after the Big Bang? How do black holes and galaxies form? How do all the stars in our galaxy move in relation to one another? To answer questions of this kind, astronomers do not just use enormous telescopes and other measuring equipment; they also use computers and smart algorithms to process the gigantic mountain of data produced by these instruments. This is why data science plays such a crucial role for Leiden astronomers.

Origin of black holes

‘Take LOFAR, for instance, a radio telescope that consists of a network of thousands of radio antennas in different European countries,’ says Huub Röttgering, Professor of Observational Cosmology and Director of the Leiden Observatory. ‘We use it to measure signals from space, from particles originating in the boundary area around black holes. Those signals give us a picture of the black holes on the edge of the universe, which were formed soon after the Big Bang and can teach us something about the origin of black holes in general.’

Map of the ‘Sausage field’, which took the supercomputer many months to calculate.

Six months of calculation

However, converting the received signals into colourful maps is a highly laborious process. ‘All the antennas together provide one terabyte of data every eight seconds,’ says Röttgering. Indicating a map of a small part of the universe, he continues: ‘This map is the outcome of eight hours of measuring, but then it took a supercomputer several months of calculating to process the data.’

This is partly due to the quantity of incoming data; for instance, how do you channel all those vast datasets to Leiden? It is also because the data has to be ‘cleaned’: all kinds of noise – including that caused by an aircraft, for instance – have to be removed. The data also need to be corrected for vibrations created by the atmosphere, and irregularities due to minuscule differences in the antennas’ receiving times have to be smoothed out by the computer later.

Developing solutions

Many other research projects like LOFAR are confronted with similar problems. The Leiden astronomers see developing solutions as a natural aspect of their discipline. ‘Reducing the calculation time by applying smart algorithms is one of the methods we use,’ says Röttgering. Another essential technique is ‘parallelisation’: breaking the calculation task into parts and using multiple processors simultaneously to perform the calculations.

Popular astronomy graduates

Developing software and hardware solutions is therefore just as important for Leiden University’s astronomers as developing theories about the universe. It is precisely this broad orientation that makes its Astronomy degree programme highly attractive to students. ‘We now have over a hundred first-year students. This is many more than in the past, but they still all find jobs,’ says Röttgering. ‘As our students learn a lot of maths and physics during their studies, and also gain hands-on experience with computer science, they’re very popular even outside astronomy.’

Leiden Observatory

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