UP-led team detects record-breaking ‘cosmic laser’ halfway across the universe

A groundbreaking study led by the University of Pretoria (UP) has opened a new radio astronomy frontier. Using the MeerKAT radio telescope and strong gravitational lensing, South African astronomers have discovered the most distant hydroxyl megamaser ever detected. The natural “space laser” is located in a violently merging galaxy more than 8 billion light-years away. 

Hydroxyl megamasers are extremely bright radio-wavelength emissions that are produced when hydroxyl molecules in gas-rich merging galaxies crash into one another. These cosmic collisions compress gas and stimulate large reservoirs of hydroxyl molecules to amplify radio emission. The physical mechanism is similar to lasers on Earth, but operates at a much longer wavelength of light of about 18cm, rather than optical light that our eyes can see. 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.

The 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’s both the most distant and luminous known system. In fact, it’s so luminous that it warrants the classification “gigamaser” rather than “megamaser”. Despite its distance, it produced a surprisingly strong signal, thanks to the combined power of the MeerKAT and strong gravitational lensing, a phenomenon originally theorised by Albert Einstein. 

“This system is truly extraordinary,” says Dr Thato Manamela, lead author of the study and a postdoctoral researcher at UP whose work is funded by the South African Radio Astronomy Observatory. “We’re 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 behave – 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, together enabling a wonderfully serendipitous discovery.”

The MeerKAT’s design makes it exceptionally well suited to detecting faint radio emissions at centimetre-long wavelengths. However, 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 to allow for the possibility of a breakthrough discovery.

“This result is a powerful demonstration of what the MeerKAT can do when paired with advanced computational infrastructure, fit-for-purpose data processing pipelines and highly trained software support personnel,” says co-author of the study Professor Roger Deane, who is the Director of the Inter-University Institute for Data Intensive Astronomy and a 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.”

Hydroxyl megamasers are a rare phenomenon. Previous studies show that they trace the most vigorous galaxy collisions, where enormous reservoirs of gas fuel intense starbursts and feed central black holes. Systematic searches – such as those conducted by deep MeerKAT surveys – promise to convert these once-rare finds into powerful probes of cosmic evolution.

“This is just the beginning,” Dr Manamela says. “We don’t want to find just one system – we want to find hundreds to thousands. At UP, we’re carrying out systematic surveys of the universe, building the required computational pipelines and algorithms to open this observational frontier ahead of, and ultimately with, the Square Kilometre Array.”

The discovery underscores South Africa’s growing leadership in data-intensive radio astronomy.

“This discovery represents UP’s leadership role in cutting-edge science and research,” says Prof Sunil Maharaj, Vice-Principal: Research, Innovation and Postgraduate Education at UP. “We are committed to building both the next generation of scientists and the computational architecture needed to further expand the frontiers of discovery. The research we are doing today with the world-leading MeerKAT telescope promises more such exciting discoveries in the future.”

The paper was accepted for publication in Monthly Notices of the Royal Astronomical Society Letters. The pre-print can be accessed here.