Astronomers detect radio signal originating from atomic hydrogen in distant galaxy

0

The astronomical distance at which this signal has been detected is the largest in terms of spacing so far, said an IISc statement. It is also the first confirmed appearance of 21 cm emission from a galaxy.

Astronomers from McGill University in Canada and the Indian Institute of Science (IISc) in Bengaluru have detected a radio signal emanating from atomic hydrogen in a distant galaxy. To capture this radio signal, they used data from the Pune-based Giant Meterwave Radio Telescope (GMRT). The astronomical distance at which this signal has been detected is the largest in terms of spacing so far, said an IISc statement. It is also the first confirmed appearance of 21 cm emission from a galaxy.

The findings related to this discovery have been published in the journal Monthly Notices of the Royal Astronomical Society. Atomic hydrogen is the basic fuel needed for star formation in a galaxy. When hot ionized gas from the galaxy’s surroundings falls on the galaxy, the gas cools and forms atomic hydrogen. It then turns into molecular hydrogen, and then stars are formed.

Therefore, there is a need to trace the evolution of neutral gas at different cosmic epochs to understand the evolution of galaxies over cosmic timescales, the statement said. Atomic hydrogen emits radio waves of wavelength 21 cm, which can be detected using low-frequency radio telescopes such as the GMRT. Thus, the 21 cm emission is a direct tracer of the nuclear gas content in both near- and far-flung galaxies.

However, this radio signal is extremely weak and due to its limited sensitivity it is nearly impossible to detect emission from the distant galaxy using current telescopes. Using the GMRT data, Arnab Chakraborty, a researcher at McGill University’s Physics and Trottier Space Institute, and Nirupam Roy, Associate Professor, Department of Physics, IISc, detected a radio signal originating from atomic hydrogen at ‘redshift Z=1.29’ in a distant galaxy.

Chakraborty said that by the time the signal from the source reached the telescope, the 21 cm emission line was spread by 48 cm due to the extreme distance of the galaxy. The captured signal was emitted from the galaxy in question when the universe was only 4.9 billion years old. In other words, the time taken to see the history of this source is 8.8 billion years.

Disclaimer:Prabhasakshi has not edited this news. This news has been published from PTI-language feed.