Distant galaxies emit powerful radio signal

Astronomers using South Africa’s MeerKAT radio telescope detected a powerful radio signal from two merging galaxies located 8 billion light-years away. This discovery, made by researchers at the University of Pretoria, was shared in February 2026 on arXiv, a preprint platform, but has not yet been peer-reviewed.

New record for radio emission distance

The signal is the farthest of its kind ever observed, surpassing the previous record of 3 billion light-years. This achievement is attributed to the improved sensitivity of the MeerKAT telescope, which allowed the detection of such a faint signal from such a great distance.

Maser mechanism amplifies the signal

The detected signal is produced by a maser, a device that emits energy in radio waves instead of visible light. In dense molecular clouds, hydroxyl radical molecules absorb infrared light from nearby stars and re-emit it in a narrow radio frequency. This process can generate a beam millions of times more powerful than ordinary masers in our galaxy, known as megamasers.

Galaxy collisions trigger megamasers

These powerful radio emissions are linked to galaxy collisions, where compressed gas leads to bursts of star formation and heated dust. The source of the signal, HATLAS J142935.3-002836, corresponds to two galaxies merging, a process similar to what will happen when the Milky Way and Andromeda galaxies collide in about 5 billion years.

Gravitational lensing magnifies the signal

A massive galaxy, invisible in radio images but positioned between the source and Earth, acted as a gravitational lens. Its gravity bent the space around it, focusing the radiation toward Earth. This effect, predicted by Einstein’s general relativity, is now a common method for studying distant objects in the universe.

Signal’s power is immense but uncertain

The detected signal appears extremely luminous, but this measurement reflects what the telescope receives, not the true power of the source. Once the gravitational lensing effect is accounted for, the actual power is less certain. The hydroxyl radiation detected is equivalent to over 300,000 suns compared to our star.

Signal from early universe era

The light from this source left its origin more than 3 billion years before the formation of the Sun and Earth. This places it in an era when the universe was less than half its current age. At such a vast distance, any detectable source must be either extremely large or significantly amplified by gravitational lensing.

Redshift measures cosmic distance

Astronomers determined the distance using redshift, a measure of how much the universe’s expansion has stretched the light’s wavelength. The redshift here is 1.027, much higher than the 0.25 seen in previously cataloged hydroxyl megamasers. This discovery expands the range of distances for such sources by four times, revealing a new era of the universe.

Discovery aids galaxy formation studies

This detection is more than a record; it provides insights into galaxy mergers throughout cosmic history. These mergers are key to understanding how galaxies form and evolve. MeerKAT, as a precursor to the Square Kilometre Array, will help detect more of these sources in the future.