Researchers from the Indian Institute of Science (IISc) in Bengaluru and astronomers from McGill University in Canada have discovered a radio signal coming from atomic hydrogen in a far-off galaxy using data from the Giant Metrewave Radio Telescope (GMRT) in Pune.
The astronomical distance across which such a signal has been detected, according to researchers, is by a significant margin the largest thus far. Also, this is the first independently verified discovery of substantial lensing of a galaxy’s 21-cm emission. The Royal Astronomical Society has finally released the results.
Atomic hydrogen, according to researchers, is the fundamental fuel needed for star formation in a galaxy.
The galaxy is covered by hot, ionised gas from the surrounding medium. As the gas cools, it generates atomic hydrogen, which later transforms into molecular hydrogen and eventually produces stars. They concluded that in order to trace the evolution of neutral gas at various cosmological epochs, one must first understand the evolution of galaxies over cosmic time.
Low frequency radio telescopes like the GMRT can detect the 21 cm radio waves that atomic hydrogen produces. Therefore, the atomic gas concentration of both adjacent and far-off galaxies may be directly measured using the 21cm emission. However, because to the existing telescopes’ poor sensitivity and the radio signal’s great weakness, it is almost hard to detect the emission from a distant galaxy.
Arnab Chakraborty, a postdoctoral researcher at the McGill University Department of Physics and Trottier Space Institute, and Nirupam Roy, an associate professor at the Indian Institute of Science, have discovered a radio signal from atomic hydrogen in a far-off galaxy using GMRT data.
According to Chakraborty, the signal from the source to the telescope redshifted the 21cm emission line to 48cm because of the vast distance to the galaxy. When the signal was produced and discovered by the team, the universe was only 4.9 billion years old.
The scientists also noted that this specific galaxy’s atomic hydrogen mass is almost two times more than its star mass. These findings show that it is possible to observe atomic gas from galaxies at cosmic distances in similar lensed systems with only a little amount of observing time.
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