A team of astronomers from the Carnegie Institution in Washington (USA) has found the brightest object ever discovered in the early universe, 13 billion light-years away. This is a quasar from a time when our universe was only 7% of its current age.
A quasar is a galaxy that orbits a supermassive black hole that is actively feeding on material. The light and radio emissions that we see are caused by the material around the black hole, called the accretion disk. This disk contains dust and gas spinning at incredible speeds – like water going down a drain – generating immense friction as it is pulled by the massive gravitational force of the central black hole. As they consume matter, they eject powerful jets of plasma at almost the speed of light.
These jets are extremely bright in the radio frequency spectrum. It was precisely this signal emanating from the recently discovered quasar, named PSO J352.4034-15.3373 (P352-15 for short), that was picked up by the Very Long Baseline Array radio telescope.
“There is a shortage of known powerful radio emitters from the early universe and this is the brightest radio quasar at that time by a factor of 10,” said astrophysicist Eduardo Bañados, leader of the study to The Astrophysical Journal that collects the job.
The observations of the aforementioned radio telescope showed that the quasar was divided into three different components , for which two possible interpretations have been exposed. The first is that the black hole is at one end, and the other two components are parts of a single jet. The second theory is that the black hole is in the middle, with a jet on each side.
According to optical telescopes, which show the quasar in visible light, the position of the black hole aligns with one of the final components, making the first interpretation the most likely. This means that by studying and analyzing the two parts of the jet, astrophysicists can measure how fast it is expanding.
On the other hand, if the black hole turns out to be in the center, it would represent that the jets are much smaller, which would evidence a much younger object, or one that is embedded in dense material that is slowing the jets.
More research will be needed to determine which of the two scenarios is the real one. Meanwhile, P352-15 remains an object of great value to scientists.
The potential of this quasar
It is not as old as J1342 + 0928 , a quasar from when the universe was only 5% of its current age, but the light from quasars can be used to study the intergalactic environment. This is because the hydrogen that makes its long journey to Earth changes the spectrum of light; recently, a quasar was used in this way to find missing baryonic matter in the space between galaxies.
“ We are seeing P352-15 as it was when the universe was less than 1 billion years old. This is almost the end of a period when the first stars and galaxies were reionizing the neutral hydrogen atoms that permeated intergalactic space. The glow of this quasar and its great distance make it a unique tool to study the conditions and processes that prevailed in the first galaxies in the universe “, clarifies astrophysicist Chris Carilli of the National Radio Astronomy Observatory .
Thus, the quasar, whose material moves at almost the speed of light, could help astronomers better understand the time when the first stars in the universe formed and began to clump together.
“The jet from this quasar could serve as an important calibration tool to help future projects penetrate the dark ages and perhaps reveal how the first galaxies were born ,” Bañados said.
Reference: Eduardo Bañados et al, A Powerful Radio-loud Quasar at the End of Cosmic Reionization, The Astrophysical Journal (2018). DOI: 10.3847 / 2041-8213 / aac511
Image credit: Artwork by Robin Dienel, Carnegie Institution for Science
