Radio signal generated by atomic hydrogen detected from a distant galaxy 8 billion light years away


Astronomers from McGill University in Canada and the Indian Institute of Science with the help of the Giant Metrewave Radio Telescope (a collection of thirty fully steerable parabolic radio telescopes situated in Pune, India) have captured a radio signal from the most distant galaxy, known as SDSSJ0826 + 5630, 8 billion light years away. The radio signal is originating from atomic hydrogen, radio waves with 21 cm wavelength. The signal was emitted when the universe was only 4.9 billion years old. The detection is helping studying the cosmic evolution hinting at how the stars formed, as atomic hydrogen serves as a fuel during star formation. This finding is also the first confirmed detection of strong lensing of 21 cm emission from a galaxy.


The detection in this case used a natural phenomenom – gravitational lensing. (The signal is bent by the presence of another massive body, another galaxy, between the target and the observer; it results in the magnification of the signal by a factor of 30). With these measurements, the team was able to estimate how much atomic hydrogen is in that distant galaxy. The value is equivalent to 900 billion Suns. The previous record holder for the most distant detection of the 21-centimeter line emitted those radio waves 4.1 billion years ago.