Astronomers have detected the brightest and most distant maser, a laser-like beam of microwaves, produced by colliding galaxies nearly 8 billion light years away. The discovery was made using the MeerKAT telescope in South Africa. This phenomenon, amplified by gravitational lensing, may represent a new category of extremely powerful masers.
Astronomers using the MeerKAT radio telescope array in South Africa have observed a powerful maser in the galaxy H1429-0028, located nearly 8 billion light years from Earth. A maser occurs when hydroxyl ions, consisting of hydrogen and oxygen, are excited to higher energy states by light passing through dust clouds in merging galaxies. These ions then relax upon stimulation by radio waves, such as those from a supermassive black hole, emitting a focused beam of microwave radiation.
The team, led by Roger Deane at the University of Pretoria, initially aimed MeerKAT—comprising 64 linked radio telescopes—at the galaxy to search for molecular hydrogen emissions at the 1667 megahertz frequency. Instead, they detected a strong signal at a higher frequency indicative of a maser. "We had a quick look at the 1667 megahertz [frequency], just to see whether it was even detectable, and there was this booming, huge [signal]. It was immediately the record," Deane said. The signal's intensity surpasses previous detections, earning it potential classification as a gigamaser, with luminosity about 100,000 times that of a star but concentrated in a narrow part of the electromagnetic spectrum.
The light from H1429-0028 is magnified by gravitational lensing from an intervening massive galaxy, enhancing its visibility. Such masers arise in specific conditions during galaxy mergers, involving compressed gas, star formation, and emissions from heated dust. Matt Jarvis at the University of Oxford noted that future observations with the Square Kilometre Array, a more sensitive successor to MeerKAT, could reveal similar masers from the universe's earliest galaxies, providing insights into ancient merger processes. "[Masers] need very precise conditions," Jarvis explained. "You need this radio continuum emission and you need this infrared emission, which you only really get from dust heated around forming stars. In order to get these very specific physical conditions to get the maser in the first place, you need merging galaxies."
This serendipitous find highlights the role of colliding galaxies in producing intense radiation phenomena observable across cosmic distances.