Irish team helps publish cosmic map revealing thousands of hidden galaxies

19 Feb 2019

A montage of low-power radio galaxies from the HETDEX region of the LoTSS survey, shown on an optical background. Image: Judith Croston and the LOFAR surveys team

Astronomers from Ireland and 17 other countries have created a new map of the known universe revealing thousands of previously hidden galaxies.

Being able to chart our course through the known universe just got a whole lot easier thanks to the creation of a new sky survey using the Low Frequency Array (LOFAR) telescope network which includes a station at Birr Castle, Co Offaly. An international team of 200 astronomers – including a number from University College Dublin (UCD) – has published its findings across 26 research papers in a special issue of the journal Astronomy & Astrophysics.

The survey revealed thousands of previously undiscovered galaxies, helping us not only better understand our place in the universe, but also reveal vital answers on the physics of black holes and how clusters of galaxies evolve.

So far, the LOFAR telescope survey has chartered only one quarter of the night sky in Earth’s northern hemisphere at low frequencies, with 10pc of the data being made public at this point in time. It maps 300,000 sources, almost all of which are galaxies in the distant universe whose radio signals have travelled billions of light years to reach Earth.

UCD associate professor John Quinn, from the college’s School of Physics, and his PhD student Sean Mooney are members of the LOFAR surveys’ key science projects and were lead authors on one of the papers published today (19 February). Their paper is focused on the jets from supermassive black holes that are pointed towards the Earth and how they could determine where black holes come from.

A false colour image a spiral galaxy in white against a light blue background.

The spiral galaxy M51 in the HETDEX region. Image: Tim Shimwell and the LOFAR surveys team

‘Black holes are pretty messy eaters’

“What we do know is that black holes are pretty messy eaters,” said Prof Huub Röttgering of Leiden University, principal investigator of the surveys team. “When gas falls onto them they emit jets of material that can be seen at radio wavelengths.”

Meanwhile, Mooney said that the LOFAR survey is “a goldmine of information for us” and that it “will surely prove to be a useful resource for many other astrophysicists around the world also”.

The technological aspect of LOFAR is also impressive in itself. All of the data gathered from the various stations in Europe is returned to the SURFsara high-performance computing centre in Amsterdam which hosts more than 20,000TB of LOFAR data. Machine-learning algorithms analyse the data to take a considerable workload off the human astronomers.

Speaking of the data, Surfsara’s Dr Raymond Oonk said: “It is the largest astronomical data collection in the world.

“Processing the enormous data sets is a huge challenge for scientists. What normally would have taken centuries on a regular computer was processed in less than one year using the high throughput compute cluster and expertise.”

Colm Gorey was a senior journalist with Silicon Republic