An article published in the journal “Astronomy & Astrophysics” reports a study on the blazar PSO J030947.49+271757.31, or simply PSO J0309+27, the farthest ever identified being about 12.8 billion light-years from Earth. A team of researchers led by astrophysics Cristiana Spingola of the University of Bologna and associated with the Italian National Institute of Astrophysics used the VLBA radio telescope to study PSO J0309+27, discovering details in a jet of materials ejected at about three quarters of the speed of light that spans about 1,600 light-years.
A blazar is a type of quasar, an active galactic nucleus, which has a jet oriented towards the Earth. It has such a brightness that it’s detectable billions of light-years away because a supermassive black hole heats the materials surrounding it to the point of generating enormous amounts of electromagnetic emissions. Some quasars, and therefore also some blazars, can have particularly high radio wave emissions and therefore be excellent subjects for observations with radio telescopes. They’re called radio-blazars and for this reason the active galactic nuclei are called radio-loud AGNs.
The blazar PSO J0309+27 was discovered by a team led by Silvia Belladitta, PhD student of the University of Insubria who was doing her thesis work at the National Institute of Astrophysics in Milan, thanks to observations conducted with the Large Binocular Telescope (LBT) and the Swift space telescope, but it was immediately noted that it was very bright in radio waves as well. The announcement of the discovery was published in March 2020 in “Astronomy & Astrophysics”.
Some of the researchers who discovered the blazar PSO J0309+27 continued to study it, this time with the VLBA (Very Long Baseline Array) radio telescope, obtaining new details thanks to its brightness in radio waves. This made it possible to discover some unusual features.
Astrophysicist Daniele Dallacasa, another of the discoverers of the blazar PSO J0309+27 who continued to study it, explained that its characteristics suggest that the researchers may have discovered a young source where the process that generates X-ray emissions is stable while the one that generates radio waves is still starting up. Another possibility is that the source is characterized by a jet that carries gas at relativistic speeds slower than nearer objects, where the jets can have speeds close to those of light and not “only” three-quarters of the spped of light.
The blazar PSO J0309+27 is about 12.8 billion light years away from Earth. This means that it was already active when the universe was less than a billion years old. It’s the farthest blazar ever discovered and it’s also the brightest radio-blazar. The most powerful radio emissions come from the active galactic nucleus, but the ones from the jet are powerful enough to span a length of approximately 1,600 light years. All this allows to study that primordial activity and to study the evolution of very ancient galaxies.
