A strong radio signal nearly 9 billion light-years away from Earth was captured in a new recording.
The signal was detected by India’s Giant Metrewave Radio Telescope. McGill University said in a release that this marked the first time this type of radio signal has been detected at such a large distance.
Researchers from McGill University and the Indian Institute of Science studied the signal and found that it was emitted when the universe was 4.9 billion years old.
The researchers said the telescope was able to capture the distant signal because it was bent by another galaxy located between the signal and the telescope.
As a result, the signal is effectively amplified up to 30 times, enabling the telescope to capture it” said Nirupam Roy, co-author of the study and associate professor at IIS India.
Scientists detected the signals by a unique wavelength known as a “21-centimeter line” or the “hydrogen line,” which is reportedly emitted by neutral hydrogen atoms.
McGill post-doctoral researcher Arnab Chakraborty said, ‘This is the equivalent of looking back 8.8 billion years in time”.
‘The astronomical distance over which such a signal has been picked up is the largest so far by a large margin. This is also the first confirmed detection of strong lensing of 21 cm emission from a galaxy’.
Atomic hydrogen is the basic fuel required for star formation in a galaxy. When hot ionized gas from the surrounding medium of a galaxy falls onto the galaxy, the gas cools and forms atomic hydrogen, which then becomes molecular hydrogen, and eventually leads to the formation of stars.
The statement said, ‘Understanding the evolution of galaxies over cosmic time requires tracing the evolution of neutral gas at different cosmological epochs’.
According to the report atomic hydrogen emits radio waves of 21 cm wavelength, which can be detected using low-frequency radio telescopes like the GMRT. Thus, 21 cm emission is a direct tracer of the atomic gas content in both nearby and distant galaxies.
However, this radio signal is extremely weak and it is nearly impossible to detect the emission from a distant galaxy using current telescopes due to their limited sensitivity.
Until now, the most distant galaxy detected using 21 cm emission was at redshift z=0.376, which corresponds to a look-back time – the time elapsed between detecting the signal and its original emission – of 4.1 billion years.
The research suggests that scientists may be able to probe the cosmic evolution of neutral gas with low-frequency radio telescopes in the near future.