Home / Science / News /  Scientists capture radio signal from galaxy 9 billion light-years away

Scientists have made a groundbreaking discovery by capturing radio signals from a galaxy located almost 9 billion light-years away from the Earth, according to space.com. This is the first time that a signal of this nature has been received from such a distance. The scientists were able to detect the signals by using a unique wavelength known as the "21-centimetre line" or the "hydrogen line," which is emitted by neutral hydrogen atoms.

By utilizing the concept of warped space-time as a magnifying glass, the astronomers have picked up the most distant signal of its kind from a remote galaxy. This discovery could open up a window of understanding into the formation of our universe.

Scientists from McGill University and Indian Institute of Science have made this groundbreaking discovery. According to a statement from Indian Institute of Science, "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."

The discovery of radio signals from a galaxy located almost 9 billion light-years away has been published in the Monthly Notices of the Royal Astronomical Society. The research provides a new perspective on how star formation is triggered in galaxies.

The key element in star formation is atomic hydrogen, which is the primary fuel required for the formation of stars. The study explains that when hot ionized gas from the surrounding medium of a galaxy falls onto the galaxy, it cools and forms atomic hydrogen. This atomic hydrogen then transforms into molecular hydrogen, eventually leading to the formation of stars.

"Therefore, understanding the evolution of galaxies over cosmic time requires tracing the evolution of neutral gas at different cosmological epochs" the statement read.

The Giant Metrewave Radio Telescope, located in Pune, India, received the record-breaking signal.
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The Giant Metrewave Radio Telescope, located in Pune, India, received the record-breaking signal. (National Centre for Radio Astrophysics)

According to report from PTI, 21 cm emission is a direct indicator of the atomic gas content in both nearby and far-off galaxies because atomic hydrogen emits radio waves of that wavelength. These waves can be detected using low-frequency radio telescopes like GMRT (Giant Metrewave Radio Telescope). This brand-new discovery presents a once-in-a-lifetime chance to research the origins of galaxies and the early universe.

However, this radio signal is incredibly weak, making it nearly impossible for present telescopes to detect the emission from a far-off galaxy.

"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 (Redshift represents the change in wavelength of the signal depending on the object's location and movement; a greater value of z indicates a farther object)," it said.

Arnab Chakraborty, a post-doctoral researcher at the Department of Physics and Trottier Space Institute of McGill University, and Nirupam Roy, Associate Professor, the Department of Physics, IISc, were able to detect the signal from the galaxy which has a redshift of 1.29. The signal was emitted from this galaxy when the universe was only 4.9 billion years old, making it the most distant signal of its kind ever detected.

"Due to the immense distance to the galaxy, the 21 cm emission line had redshifted to 48 cm by the time the signal travelled from the source to the telescope," says Chakraborty. This discovery allows scientists to study the early universe and the formation of galaxies in a new way, and it will help to understand the evolution of neutral gas at different cosmological epochs.

This discovery was made possible by a phenomenon known as gravitational lensing, in which the light from the source is bent due to the presence of another massive body, such as an early type elliptical galaxy, between the target galaxy and the observer, essentially "magnifying" the signal.

Roy explained, "In this specific case, the magnification of the signal was about a factor of 30, allowing us to see through the high redshift universe."

These results demonstrate the feasibility of observing atomic gas from galaxies at cosmological distances in similar lensed systems with a modest amount of observing time.

This discovery opens up new possibilities for studying the cosmic evolution of neutral gas with existing and upcoming low-frequency radio telescopes in the near future.

Yashwant Gupta, Centre Director at the National Centre for Radio Astrophysics (NCRA) said, "Detecting neutral hydrogen in emission from the distant Universe is extremely challenging and has been one of the key science goals of GMRT. We are happy with this new path-breaking result with the GMRT, and hope that the same can be confirmed and improved upon in the future."

This research provides a new perspective on how galaxies formed and evolved in the early universe, and it will help scientists to understand the evolution of neutral gas at different cosmological epochs.

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