A radio signal has been picked up by astronomers from the most distant galaxy known to mankind with a unique wavelength known as the “21-centimeter line” or the “hydrogen line,” emitted by neutral hydrogen atoms.
The Giant Metrewave Radio Telescope in India detected the hydrogen line from a faraway galaxy. The hydrogen line occasionally allows scientists to get a glimpse into the most remote areas of the universe. Remarkably, this means that scientists are now capable of further investigating the origin of the first stars and galaxies that are most distant from our own planet.
The star-forming galaxy SDSSJ0826+5630 sent out its unique signal when our galaxy, which is now 13.8 billion years old, was then just 4.9 billion years old at the time. Hence, it is like taking a look into the very early times of the universe. The researchers were able to determine the gas mass of the galaxy by using the specified signal, and it was found to be roughly twice as massive as the earliest visible stars.
“It’s the equivalent to a look-back in time of 8.8 billion years,” Arnab Chakraborty, the lead author, who is a post-doctoral cosmologist of the McGill University Department of Physics, said of the breakthrough in a statement.
“A galaxy emits different kinds of radio signals,” he explained. “Until now, it’s only been possible to capture this particular signal from a galaxy nearby, limiting our knowledge to those galaxies closer to Earth.”
Difficult to detect hydrogen line signal
Spotting these wavelengths from more distant galaxies is challenging because the electromagnetic radiation from early galaxies experiences wavelength stretching and energy reduction as it travels huge distances to Earth.
Therefore, telescopes on Earth require a natural boost to detect radio waves with long wavelengths and low energy, such as that of the hydrogen line signal.
However, the team broke the record by using a phenomenon foreseen by Einstein’s geometric theory of gravitation, first proposed in 1915. This was also a part of the general theory of relativity.
— SPACE.com (@SPACEdotcom) January 20, 2023
Gravity as an early universe window
According to general relativity, things with mass bend spacetime in the same way as a ball put on a stretched rubber sheet would. The larger the mass, the more severe the curvature.
Much like a bowling ball would create a significant curve in the rubber sheet, a black hole or galaxy would have a similar effect in spacetime.
This warping of spacetime causes light to bend when it passes by objects that have a high mass. A phenomenon known as gravitational lensing occurs when a foreground or lensing item with a great mass lies between an observer and a background source.
This causes the light from the background object to bend and take multiple courses through and around the lensing object. Not only may this cause a single item to appear at several spots in the sky, but it can also intensify the light. This generally allows for a better look into the universe.