Australian astronomers have captured the most sensitive radio image of a ball of tightly-packed stars, known as a globular cluster.
The image of 47 Tucanae, the second brightest globular cluster in the night sky, was produced by the Curtin University branch of the International Centre for Radio Astronomy Research in Western Australia.
It took more than 450 hours of observations on an Australia Telescope Compact Array (ACTA) to capture the ultra-sensitive image.
The project had stretched the telescope's capabilities to its limits, co-author Tim Galvin said.
"(It) represents a culmination of years of research and technological advancements," Dr Galvin said.
"ATCA's ultra-deep image of 47 Tucanae represents just the beginning of the discoveries that are yet to come."
The scientists also detected a previously undiscovered radio signal from the centre of the cluster.
Lead author Alessandro Paduano said the signal could come from a black hole with a mass somewhere between supermassive black holes.
"If this signal turns out to be a black hole, it would be a highly significant discovery and the first ever radio detection of one inside a cluster," he said.
The second possible source of the signal is a pulsar - a rotating neutron star that emits radio waves.
"A pulsar this close to a cluster centre is also a scientifically interesting discovery, as it could be used to search for a central black hole that is yet to be detected," Dr Paduano said.
Ultra-sensitive images of space could become more common with next-generation SKA radio telescopes being built in Australia and South Africa.
"We managed to achieve close to SKA-quality science with the current generation of radio telescopes," astronomer Arash Bahramiana said.
"It gives us a glimpse of the exciting capabilities the next generation of radio telescopes will achieve when they come online."
The new image and research were published in the peer-reviewed Astrophysical Journal on Tuesday.
