Dr Leah Morabito part of international team detecting previously unknown galaxies

Dr Leah MorabitoDr Leah Morabito, Millard and Lee Alexander Postdoctoral Research Fellow and Postdoctoral Research Assistant in Galaxy Evolution, is among an international team of astronomers who are releasing data from a major new radio sky survey which has revealed hundreds of thousands of previously undetected galaxies, shedding new light on many research areas including the physics of black holes and how clusters of galaxies evolve. The team of more than 200 astronomers from 18 countries is publishing the first phase of the survey at unprecedented sensitivity using the Low Frequency Array (LOFAR) telescope.

Radio astronomy reveals processes in the Universe that we cannot see with optical instruments. In this first part of the sky survey, LOFAR observed a quarter of the northern hemisphere at low radio frequencies. On 19th February 2019 around ten percent of that data was made public. It maps three hundred thousand sources, almost all of which are galaxies in the distant Universe; their radio signals have travelled billions of light years before reaching Earth. The survey is particularly looking at the radio emission from black holes and clusters of galaxies.

LOFAR produces enormous amounts of data - the equivalent of ten million DVDs of data has been processed to create the low-frequency radio sky map. A large international team has been working to efficiently transform the massive amounts of data into high-quality images. Pre-processing of the LOFAR data within the archives in the Netherlands, Germany and Poland reduces the size of the huge LOFAR datasets before the data are transported to member institutions for the images to be made.

The LOFAR telescope is unique in its capabilities to map the sky in fine detail at metre wavelengths and is considered to be the world’s leading telescope of its type. The European network of radio antennas spans seven countries and includes the UK station at STFC RAL Space’s Chilbolton Observatory in Hampshire. The network is operated by ASTRON in The Netherlands.

The signals from all of the stations are combined to make the radio images. This effectively gives astronomers a much larger telescope than it is practical to build – and the bigger the telescope, the better the resolution. The first phase of the survey only processed the data from the central stations located in the Netherlands, but UK astronomers are now re-processing the data with all of the international stations to provide resolutions twenty times better. “We will be able to identify hidden black holes, study individual clouds of star formation in nearby galaxies, and understand what jets from black holes look like in the most distant galaxies,” says Leah Morabito, University of Oxford. “This extra phase of the survey will be truly unique in the history of radio astronomy, and who knows what mysteries we’ll uncover?”. Going forward, the team aims to make sensitive high-resolution images of the whole northern sky, which will reveal 15 million radio sources in total.

A special issue of the scientific journal Astronomy & Astrophysics is dedicated to the first 26 research papers describing the survey and its first results. A quarter of the papers were led by UK scientists; Dr Morabito is first author on one, and co-author on 13 more papers, including the survey description papers.

In the paper on which she is first author, Dr Morabito looks at understanding where the radio emission is coming from in a special type of galaxy: these galaxies show signs of extreme outflows driven by a super-massive black hole in their centres. She says, "we think these outflows somehow impact what goes on in the rest of the galaxy and can change the way they evolve, but we don't understand this yet. My results show that in addition to the normal star formation in a galaxy, there may be radio emission from jets connected to the black hole. As the survey progresses, we'll be able to investigate this further." You can read the article in full on the Astronomy & Astrophysics website

Find out more on the surveys website: www.lofar-surveys.org.