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Durham University

Durham University News


How giant radio telescopes will tell us more about black holes

(11 May 2021)

Dr Leah Morabito, Centre for Extragalactic Astronomy

Dr Leah Morabito, in our Centre for Extragalactic Astronomy, is a leading figure in two international radio telescope projects that will help us see more of the universe and give us new insight into distant galaxies and black holes. Find out more about Leah’s story.

Ever since seeing the movie Contact, I wanted to be a radio astronomer. In the movie, Jodie Foster’s character uses both the Arecibo telescope (which was featured in the James Bond Goldeneye movie, but unfortunately collapsed recently) and the Very Large Array, two iconic radio telescopes. Although I have used the Very Large Array to study nearby galaxies, my focus for the past few years has been on the Low Frequency Array (LOFAR), and designing data processing techniques to achieve the highest possible resolution with it. I then use these high resolution radio images to study black holes in distant galaxies.

LOFAR is a radio telescope made from dipole antennas, similar to those you find on a car, collected into ‘stations’ which are spread throughout Europe. These antennas are sensitive to radio frequencies just above and below the FM radio band (we can’t “see” through the FM radio band as it is too noisy here on Earth). We can combine the signals from all of these antennas to make a picture of what the radio sky looks like. At these low radio frequencies, the radio emission from galaxies is naturally brighter, meaning we have a better opportunity to study them. 

Radio waves

Typically only the stations located in the centre of the LOFAR array are used for imaging. The telescope is plagued by the ionosphere, which can corrupt the incoming radio waves. We correct for this when we process the data, but it is technically challenging. Using the data from even more distant LOFAR stations makes it even more challenging! But just like a camera, the bigger the lens, the better the resolution – by using all of the LOFAR stations, instead of just the central ones, we can get 20 times better resolution, which means better images of galaxies with black holes

I have been leading the efforts to make a data processing pipeline for this high resolution imaging, and my paper which describes this publicly available code and the methodology behind it was recently accepted for publication. It will be part of a special issue of the Astronomy & Astrophysics journal, along with around 10 other papers, led by early career researchers, using the pipeline for science results. These exciting papers use the high resolution to look at the sub-structure in galaxies which have super-massive black holes that launch jets of plasma, which are visible to LOFAR. The pipeline I developed will allow astronomers to make similar high-resolution images without having to spend years first becoming an expert!

Galaxy surveys

My own science interests lie in how super-massive black holes co-evolve with their host galaxies. The high resolution imaging with LOFAR will allow me to simultaneously measure radio light from star formation and any activity related to the black hole, and I will be able to build up a picture of a feedback loop between these two processes. I was awarded a UKRI Future Leaders Fellowship to carry out this work, and I’m building up a diverse team of PhD students and Post-Doctoral Research Assistants (PDRAs) to help process the first high-resolution radio survey of the Northern sky with LOFAR. My team includes a PDRA coming from South Africa, and two UK PhD students.

Our work will be crucial for helping design galaxy surveys with the Square Kilometre Array (SKA), a next-generation radio telescope that will begin construction this year. The SKA will be located in Australia and South Africa, but the headquarters are here in the UK. I sit on the UK SKA Science Committee, and helped organise a UK Town Hall meeting in March for scientists working on preparatory work for the SKA. Both LOFAR and the SKA will look deeper into the low-frequency radio sky than ever before, and help us understand how black holes have shaped our Universe today.

Find out more