The Giant Metrewave Radio Telescope (GMRT) in India has picked up a 21 cm wavelength signal, also known as the "neutral hydrogen radio link", from a galaxy at a record distance of 8.8 billion light-years from Earth.

The galaxy, designated SDSSJ0826+5630, produced this signal 8.8 billion years ago. He made it possible to estimate the content of gas in the galaxy and find out that its mass is twice the mass of visible stars in it. Galaxies produce electromagnetic radiation in a wide range, however, so far it has been possible to receive signals from the radio line of neutral hydrogen only from nearby, and therefore, younger sources.

The difficulty of receiving signals at these wavelengths from more distant galaxies is due to the fact that when overcoming large distances, the wavelengths of such signals increase, which leads to a decrease in the wave energy. Scientists were helped by the phenomenon of gravitational lensing, predicted in the general theory of relativity (GR) more than a century ago.

General relativity suggests that objects with mass distort space and time, the greater the mass, the stronger the curvature. The trajectory of the movement of light passing by a massive object is also bent - as a result, its source may appear at several points in the sky, and the signal strength may increase.

The radio signal produced by SDSSJ0826+5630 was amplified 30 times by another galaxy acting as a lensing body, as a result of which a telescope located on Earth was able to receive this signal. This means that similar signals can also be received from other distant galaxies, and long-wavelength radio telescopes will help to better study the mechanisms of evolution of objects in the young Universe.

The results of the study are published in the March issue of the British scientific journal Monthly Notices of the Royal Astronomical Society.