An illustration of the distant galaxy eight billion light-years away (red), magnified by an unrelated foreground disk galaxy, resulting in a red ring. (Image source: Inter-University Institute for Data-Intensive Astronomy)
Astronomers using the MeerKAT radio telescope in South Africa have discovered the most distant hydroxyl megamaser ever detected.
This is according to the South African Radio Astronomy Observatory (SARAO), which says the megamaser is located in a violently merging galaxy more than eight billion light-years away, opening a new radio astronomy frontier.
The MeerKAT radio telescope, located in South Africa’s Karoo region, was inaugurated in 2018 as a precursor to the Square Kilometre Array.
Consisting of 64 dishes, it quickly became one of the world’s most sensitive radio telescopes. MeerKAT has delivered landmark results, including ultra-detailed images of the Milky Way’s centre, the discovery of giant radio galaxies spanning millions of light years, studies of cosmic magnetism, and precise measurements of neutral hydrogen in distant galaxies.
It has also contributed to pulsar timing research and fast radio burst detections, demonstrating Africa’s growing leadership in global radio astronomy.
SARAO explains that hydroxyl megamasers are natural “space lasers” – extremely bright radio-wavelength emissions produced when hydroxyl molecules in gas-rich, merging galaxies crash into one another.
It notes that these cosmic collisions compress gas and stimulate large reservoirs of hydroxyl molecules to amplify radio emission.
According to the organisation, the physical mechanism is very similar to lasers on Earth, but operates at a much longer wavelength of light of about 18 centimetres, rather than optical light that our eyes can see.
It points out that when this special radio light is exceptionally bright, it is termed a megamaser – a “cosmic beacon” that can be seen across vast stretches of the universe.
“This newly-discovered system, HATLAS J142935.3–002836, is so distant that we are seeing it as it was when the universe was less than half its present age. It is both the most distant and luminous known. In fact, it is so luminous that it warrants the classification gigamaser, instead of megamaser,” SARAO adds.
Despite its distance, it produced a surprisingly strong signal, which is thanks to the combined power of MeerKAT and a phenomenon known as strong gravitational lensing, which was theorised by Einstein, it notes.
“This system is truly extraordinary,” says Dr Thato Manamela, SARAO-funded postdoctoral researcher at the University of Pretoria and lead author of the new study. “We are seeing the radio equivalent of a laser halfway across the universe.
“Not only that, during its journey to Earth, the radio waves are further amplified by a perfectly aligned, yet unrelated foreground galaxy. This galaxy acts as a lens, the way a water droplet on a window pane would, because its mass curves the local space-time. So, we have a radio laser passing through a cosmic telescope before being detected by the powerful MeerKAT radio telescope – all together enabling a wonderfully serendipitous discovery.”
SARAO adds that MeerKAT’s design makes it exceptionally well-suited to detect faint radio emission at centimetre wavelengths.
However, it notes that collecting the data is only part of the challenge – astronomers must carefully calibrate and analyse terabytes of information using sophisticated algorithms and scalable computing platforms, before any breakthrough discoveries are possible.
“This result is a powerful demonstration of what MeerKAT can do when paired with advanced computational infrastructure, fit-for-purpose data processing pipelines, and highly-trained software support personnel,” says Professor Roger Deane, co-author of the study and director of the Inter-University Institute for Data Intensive Astronomy, as well as professor at the universities of Cape Town and Pretoria.
“This synergistic combination empowers young South African scientists, like Dr Manamela, to lead cutting-edge science and compete with the best in the world.”
