Lofar telescope is a ‘major step forward for Irish astronomy’
The Irish node of Lofar, the world’s largest radio telescope – a tool that can be used around the clock and in any weather – will be up and running this year
Using Lofar, a new radio telescope, astronomers have produced one of the best images ever made at the lowest frequencies of giant bubbles produced by a super-massive black hole. On left, radio and optical; right, optical only
A convoy of 30 articulated trucks will depart the Netherlands towards the end of summer and head for Birr, Co Offaly. Their cargo? The components needed to build the Irish node of the world’s largest radio telescope.
The existing telescope, which is known as Lofar (Low Frequency Array), already has 50 nodes across Europe, allowing it to study deep space in amazing detail. But Lofar’s view of the universe will improve by 30 per cent once the Irish node becomes active by the end of this year.
“The Irish node is a major expansion, and the telescope’s sensitivity will be improved as well,” says Prof Peter Gallagher of Trinity College Dublin. He leads the Irish Lofar consortium, a collection of universities and institutes of technology that banded together to campaign for an Irish node.
The project became a reality when the Government in January announced a State contribution of €1.4 million for the project. This plus another €500,000 from the universities and philanthropic donations will get the project up and running on the Birr Castle demesne.
Lofar is a huge, €200 million international undertaking. There are 50 Lofar stations in countries including the Netherlands (where the headquarters are), Germany, France, Poland, Sweden and the UK.
Radio telescopes work the same way as regular optical telescopes but they “see” radio frequency waves rather than light. We cannot see what the radio telescopes can, but when the waves they capture are processed by a super-computer, images of objects can be produced that we can see and study, says Terry Moseley, president of the Irish Astronomical Association.
“You plot a graph of radio intensity across the object, looking at different wavelengths to read things such as energy, temperature and physical characteristics.”
As with any radio signal, you need an antenna to capture it, and this is what will fill the 30 trucks heading our way.
There are about 100,000 individual antennae in place at these stations, where they are installed in football pitch-sized clusters. Ireland’s node will have 200 of these antennae.
“They sit on the ground and grass can grow between them. They are not the prettiest things,” says Gallagher. “They are cheap as chips. They are described as the Ikea of radio astronomy, flat-pack radio astronomy. They wanted them cheap so they could be placed all over Europe.”
The antennae are spread out as far apart as possible because the longer the “baseline” distance between the farthest points east and west, the better the image the telescope can capture. This is why Irish membership doesn’t just help our astronomers but also improves the sensitivity of the telescope for all of the consortium partners.
“It is a major step forward not just for Irish astronomy but internationally,” Moseley says. “It extends the range of the telescope quite significantly. The larger the baseline the better the results you get.”
The Irish node will increase the baseline to 1,900km, the distance between Birr and the most easterly node in Lazy, Poland.
The big advantage of radio astronomy is that it works at any time and no matter what the weather. Radio waves pass through clouds and don’t suffer interference from sunlight.
“I can’t wait to turn it on and see the Milky Way and stars during the day,” Gallagher says.
The Birr necessities
The Birr Castle demesne offers advantages as a node. “Birr is still very radio quiet: we don’t get a lot of radio interference there,” Gallagher says.
Birr Castle is also home to the Leviathan, the world’s largest telescope from when it was built by the third earl of Rosse in 1845 until 1917.
Significant discoveries were made there despite the climate, including the discovery of spiral galaxies. “Maintaining the astronomical heritage at Birr is important,” says Moseley.
Most significantly, the Lofar project will give Ireland its first internationally recognised astronomical research centre of a world standard. “This gives Irish students an opportunity to work in Ireland on a cutting-edge telescope,” says Gallagher.
“It is the best news we have had in astronomical science for a long time,” adds Moseley.
There will be no shortage of areas where access to such a telescope can make a difference. Solar science, cosmology, the search for exoplanets and the study of black holes are all options. So too is Seti, the Search for Extraterrestrial Intelligence. “There are also people searching for evidence of life,” Gallagher says.
The sky is no limit when our Lofar node goes live this year.
RADIO TELESCOPES: LOFAR PROVES ITS STAR QUALITY
Radio telescopes provide astronomers with a new way of visualising the night sky. It means what is invisible in optical wavelengths can suddenly become visible in radio wavelengths.
Dr Eamon O’Gorman, a fellow at the Dublin Institute for Advanced Studies, is using radio telescopes including Lofar to see exoplanets in orbit around distant stars.
The brightness of stars makes it a challenge to see planets, but if you switch to radio waves the stars suddenly go dark and the planets light up and shine in an Aurora Borealis-like way.
“This has never been detected before,” says O’Gorman. “Lofar is ideal for this because it can go to very long wavelengths in radio waves.” He hopes to better understand what happens to stars in their last million years of life.
His supervisor, Prof Tom Ray, meanwhile, is studying stars in their first million years. Active young stars sent out jets of particles and the professor of astronomy at Dublin Institute for Advanced Studies wants to know more about these jets. “We have been imaging them with Lofar at the lowest frequencies ever recorded,” Ray says. “Our sun would have done the same thing: produce supersonic jets of material.”
O’Gorman has been using Lofar but also large arrays based in Chile and Mexico. Astronomers can bid for time on these arrays, but as a member of Lofar, Irish astronomers will have better access to pursue their research.