Astronomers from Montreal and India captured a radio signal from the farthest distant galaxy to date using a wavelength known as the 21 cm line, allowing them to see into the secrets of the early universe. Data from the Giant Meterwave Radio Telescope (GMRT) in Pune, India, was used by researchers from McGill University in Canada and the Indian Institute of Science (IISc) in Bengaluru to find a radio signal emerging from atomic hydrogen in a distant galaxy.
The astronomical distance across which this signal was detected is by far the biggest recorded to date. This is the first time that significant lensing of 21 cm galaxy emission has been seen. The findings were reported in the Monthly Notices of the Royal Astronomical Society.
A galaxy produces a variety of radio waves. Until recently, catching this signal from a neighbouring galaxy was only possible, limiting our knowledge to the galaxies closest to Earth Arnab Chakraborty, a Postdoctoral Researcher at McGill University working with Professor Matt Dobbs, says.
However, because of a natural phenomenon called as gravitational lensing, we may be able to detect a weak signal from an incredible distance. This will help us comprehend the nature of galaxies located at far greater distances from Earth, he claims.
Arnab Chakraborty, a postdoctoral researcher at McGill University’s Department of Physics and Trottier Space Institute, and Nirupam Roy, an associate professor at IISc’s Department of Physics, found a radio signal from atomic hydrogen in a distant galaxy at redshift z=1.29 using GMRT data.
Because of the immense distance between the galaxy and the telescope, the 21 cm emission line had redshifted to 48 cm by the time the signal arrived, Chakraborty adds. The signal was emitted by this galaxy when the universe was just 4.9 billion years old; the source’s look-back time is 8.8 billion years.
This identification was made possible through gravitational lensing, a phenomenon in which the light emitted by the source is deflected by the presence of another massive object, such as an early-type elliptical galaxy, between the target galaxy and the observer, magnifying the signal. In this specific case, the signal was amplified by about a factor of 30, allowing us to see through the universe‘s high redshift, Roy writes.