Most distant radio galaxy discovered beams signals from 12 billion light-years away
An international team of astronomers has detected the most distant radio galaxy ever observed. By measuring the redshift of its light, the researchers determined that the object is about 12 billion light-years away, which dates it back to when the universe itself was just a kid.
Radio galaxies are a kind of active system that are particularly chatty in radio wavelengths, thanks to the huge jets of relativistic particles they spew forth from the supermassive black holes at their centers.
This particular radio galaxy has been named TGSS J1530+1049, and it was initially discovered using the Giant Meter-wave Radio Telescope (GMRT) in India. The team, made up of researchers from the Netherlands, Brazil, Italy and the UK, then measured the redshift of the galaxy's light to determine how far away it is, using the Gemini North telescope in Hawaii and the Large Binocular Telescope in Arizona.
Light from an object that's moving away from us will appear more red than it actually is, thanks to the Doppler effect. That's because those light waves are stretched out as the universe expands, shifting the wavelengths towards the red end of the spectrum. Using that redshift, scientists can calculate how far away, and therefore how old, that object is.
This radio galaxy has a redshift of z = 5.72, indicating that it's almost 12 billion light-years away. By extension, that means the light is 12 billion years old, so it flickered on when the universe was "only" a billion years old – a baby of just seven percent of its current age.
Interestingly, these kinds of active galaxies originally weren't expected to exist that early in the universe's evolution. It was believed that it would generally take longer for the supermassive black holes at their centers to develop, but this find is just the latest to suggest that it must happen quicker than previously thought.
"Bright radio galaxies harbor supermassive black holes," says Huub Röttgering,co-author of the study. "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."
TGSS J1530+1049 has managed to topple an almost 20-year recordholder – the previous most distant radio galaxy was TN J0924-2201. Discovered in 1999, at a redshift of z = 5.19, it lies nearly 11 billion light-years away.
The research was published in the Monthly Notices of the Royal Astronomical Society.