A team led by PhD student Aayush Saxena from Leiden Observatory in the Netherlands just broke a 20-year-old record of the most distant radio galaxy ever discovered.
Initially using the Giant Meter-wave Radio Telescope (GMRT) in Khodad (near Pune), Maharashtra, the astronomers identified a galaxy from a time when the universe was only seven percent of its current age. The distance to the galaxy, located 12 billion light-years away, was later determined using Hawaii’s Gemini North telescope and the Large Binocular Telescope in Arizona.
GMRT is an array of thirty fully steerable parabolic radio telescopes of 45-metre diameter. It is operated by the National Centre for Radio Astrophysics and the Tata Institute of Fundamental Research.
A redshift of z=5.72 meant that the galaxy was perceived as it looked when the universe was only a billion years old, according to the study in the journal Monthly Notices of the Royal Astronomical Society. This also means that we are now seeing what the galaxy looked like 12 billion years ago.
“It is very surprising how these galaxies have built up their mass in such a short period of time,” Saxena said.
“Bright radio galaxies harbour supermassive black holes. It is amazing to find such objects as early in the history of the universe; the time for these supermassive black holes to form and grow must have been very short,” Huub Rottgering, also from Leiden Observatory, said. The team consists of astronomers from the Netherlands, Brazil, the United Kingdom and Italy.
Radio galaxies are very rare objects in the universe. They are colossal galaxies with a supermassive black hole in their centre that actively accretes gas and dust from its surroundings.
This activity initiates the launch of high-energy jet streams, which are capable of accelerating charged particles around the supermassive black hole to almost the speed of light. These jets are very clearly observed at radio wavelengths.
The fact that such galaxies exist in the distant universe has surprised multiple astronomers. The discovery of such galaxies at extremely large distances is important for our understanding of the formation and evolution of galaxies, researchers said.
Studying these radio galaxies in detail also sheds light on the formation of primordial black holes, which have driven and regulated the growth of galaxies, they said.