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Roland Timmerman/LOFAR

Most detailed galaxy photos yet are world news

Media all around the world reported about it: the most detailed images yet seen of galaxies, shot by radio telescope LOFAR. The international team behind these amazing results were led by Leah Morabito at Durham University and included three talented Leiden astronomers.

‘Astronomers see galaxies in ultra-high definition’, the BBC headlined about the astonishing results, which took almost a decade of work. Media in China, Indonesia, Spain and the US also reported about the research, to name a few. A special issue of the journal Astronomy & Astrophysics came out on 17 August, dedicated to 11 papers describing the results. Read all about the discovery in the press release by ASTRON. 

PhD candidates Christian Groeneveld, Roland Timmerman and Frits Sweijen from the Leiden Observatory contributed to the studies. They each tell something about their efforts and experiences. 

Christian Groeneveld

‘I focus more on the lowest frequencies of radio waves that we can see from Earth. These radio waves are very difficult to observe because they get heavily distorted by the atmosphere. However, using LOFAR we can achieve a very high resolution at these frequencies, a resolution that is more than 10 times better than previous work. 

This is particularly important when we study black holes in the centre of distant galaxies. These black holes emit hot plasma, which is particularly bright at low frequencies. At lower frequencies, we unravel older plasma, in a similar way that we find older artefacts in deeper layers of the Earth. Combined with the high resolution unlocked with LOFAR, we can trace back the behaviour and evolution of these black holes back in time.’

Roland Timmerman

‘During the second year of my PhD, I worked on a project based on LOFAR observations of Hercules A. This radio source is created by a black hole in a galaxy at a distance of about 2 billion lightyears. The two jets of plasma emitted near the black hole escape the galaxy and form gigantic radio lobes as they eventually come to a stop. 

Hercules A is known for having a fascinating ring pattern in its radio lobes, but for decades it remained unclear what caused such a pattern to emerge. Our new LOFAR observations were able to detect these ring structures with enough detail to constrain the shape of their radio spectrum, which forms an important piece of the puzzle. 

Our research not only provided us with valuable information about the physics that plays a role within radio lobes, but it was also an important test of LOFAR's capabilities, which it passed with flying colours. 

The success of this project highlights the value of collaboration in science. Without so many scientists and engineers from so many different European countries coming together to each contribute their expertise, this project would have been impossible. I feel very grateful and lucky that I have had the opportunity to contribute my part.’

Frits Sweijen

‘I contributed to this research with a paper on the galaxy 4C 43.15. The light we receive from this object originated from a time when the Universe was only 2.6 billion years old. In addition to being far away, 4C 43.15 has what we call a steep spectrum. This means the energy at certain radio frequencies gets radiated away quicker than one would initially expect.

Talking from the perspective of my paper, these results will further our understanding of the formation and evolution of small and distant radio galaxies. While the current studies only focused on a single object, LOFAR's large field of view ensures that in the future we can study sources across the entire Northern sky.

Working within the collaboration has been a great example of how such an international instrument can also spur international collaboration. It feels exciting to be part of such a large collaboration.’

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