MeerKAT Detects the Most Distant Cosmic 'Laser' Ever Found, From 8 Billion Light-Years Away

Astronomers using South Africa's MeerKAT radio telescope have identified the farthest hydroxyl megamaser ever observed, a natural radio-wave 'laser' coming from a galaxy merger more than 8 billion light-years away. The researchers, Thato Manamela, a postdoctoral researcher at the University of Pretoria, and Roger Deane, director of the Inter-University Institute for Data Intensive Astronomy (IDIA) and a professor at the universities of Cape Town and Pretoria, described the find as a new frontier in radio astronomy.

Because light from the galaxy has taken more than 8 billion years to reach Earth, astronomers are seeing it as it looked when the universe was less than half its current age of about 13.8 billion years, a period when galaxies collided more often and were far more active than the mature galaxies seen nearby today.

A hydroxyl megamaser is millions of times more luminous than a standard maser found in the local universe; a gigamaser, by comparison, is a billion times more luminous, or 1,000 times more powerful than a megamaser. Detecting a signal this faint and distant would typically take hundreds of hours of observing time, but the team found it in just five hours, aided by gravitational lensing from a foreground galaxy that amplified the signal. The researchers were originally targeting neutral hydrogen gas when MeerKAT's wide bandwidth allowed the surprise detection of the megamaser signal in the same data.

The discovery relied on MeerKAT's sensitivity and wide frequency coverage, which let astronomers detect both the hydroxyl line and neutral hydrogen absorption in a single observation, something that previously took two separate observations with older technology. Processing the data, which arrives at gigabytes per second, required high-performance computing at IDIA and calibration pipelines running trillions of calculations over several days to turn the raw radio signal into a usable result.

The rapid detection suggests future surveys with MeerKAT and the upcoming Square Kilometre Array (SKA) Observatory could uncover many more such distant, extreme objects. The SKA's SKA-Low and SKA-Mid arrays will cover low-to-mid radio frequencies, while the planned U.S. facility ngVLA will operate at higher frequencies, together forming major pillars of next-generation radio astronomy, the researchers said.