The Crab Nebula, which contains the Crab Pulsar. Image combines optical data from Hubble (in red) and X-ray images from Chandra (in blue).
Credit: NASA/CXC/ASU/J. Hester et al
SYDNEY: Thirty thousand more spinning, highly magnetised pulsars are likely to be found with the help of giant telescope arrays, according to scientists who predict that they will revolutionise studies of gravity.
In research to be published in June by the journal Astronomy & Astrophysics an international team of astronomers have reported the first results from LOFAR (LOw Frequency Array), a multi-antenna observatory spread across Europe.
Pulsars - massive stars that spin with extreme accuracy - were first discovered in the 1960s and are one of the prime targets of LOFAR. Because of their exceptional regularity, they provide a 'clock' that can be used to detect the effect of gravity waves, a feature of general relativity predicted by Einstein but never detected.
"We are returning to the frequencies where pulsars were first discovered, but now with a telescope of a sophistication that could not have been imagined back in the 1960s," said lead author and astrophysicist Ben Stappers, from the University of Manchester in the UK.
Testing gravity
LOFAR operates at a low frequency, looking at radio waves between 10 to 240 megahertz. The advantage is a clear view of pulsars without interference from intervening electromagnetic radiation.
"You can measure known arrival times of pulsars with much greater precisions and it will allow completely new tests of relativity," co-author and astrophysicist Michael Kramer told Cosmos.
Kramer, the director of the Max-Planck-Institute for Radio Astronomy, in Bonn, Germany and from the Jodrell Bank Centre for Astrophysics at the University of Manchester, said researchers currently know of 2,000 pulsars in the galactic plane.
All-sky surveys with Parkes radio telescope in Coonabarabran, New South Wales, in the southern sky and Northern Hemisphere equivalents soon expect to find another 500 or so, he said.
But planned radio astronomy observatories such as the Square Kilometre Array (SKA) - a continent-wide 3,000 dish array planned for either South Africa or Australia and New Zealand - will increase this by a factor of 10, he added.
Thousands of flashing stars
"We estimate the total number will be around 20,000 and we estimate the SKA will find every pulsar that is beamed towards the Earth - a factor of 10 over what we know today," said Kramer.
The pay off will be a better chance to pin down the elusive gravity waves predicted by Einstein. "We'll be able to time pulsars 100 times better and be able to study gravitational waves at much higher frequencies," he said.
John Reynolds, a systems scientist at CSIRO Astronomy and Space Science in Sydney, who was not involved in the research, said the early results from LOFAR were "very interesting".
"Pulsars are just fantastic, that's why we want to find them," he said. "They're extremely interesting in their own right in terms of their physical properties - they are probes into high energy physics, strong magnetic fields and they are also tests of general relativity."
Observing pulsars as they beam towards Earth from different directions in space would allow astronomers to detect minute differences as the signals arrive, caused by gravity waves distorting space-time in different directions, said Reynolds.
"If it's true that gravity waves exist and they are moving through space, you'd expect one of these 'clocks' to be running a little slow."
The Dish is next to Parkes
In the article, the Parkes Radio telescope should be next to the town of Parkes, not Coonabarabran.