After the universe was created, it took a few million years for the first light to shine across the cosmos. The first stars began forming, and so did ancient galaxies. As the gas and dust at the center of these galaxies began to spiral around their supermassive black holes, they formed the brightest objects in all of the universe — quasars.
Quasars give us a peek into what the universe looked like during its infancy, and scientists are able to look back at these cosmic beasts through telescopic time travel.
A team of researchers recently announced the discovery of the most distant quasar ever observed, dating back to 670 million years after the Big Bang. The quasar was accompanied by the oldest black hole ever observed. But this black hole's extreme age isn't its only notable feature — it is absolutely (super)massive. And scientists also can't explain how it reached its extreme size.
The discovery was announced on Tuesday during the 237th Meeting of the American Astronomical Society, and is detailed in a study accepted for publication in the Astrophysical Journal Letters.
HERE'S THE BACKGROUND — Quasars were discovered in the 1960's. Their name is derived from them being 'quasi-stellar objects,' as a single quasar emits the same amount of light as a trillion stars, all the while occupying an area of space that is smaller than our Solar System.
Scientists believe quasars form when galaxies have an abundant amount of gas and dust surrounding the black holes at their center, which eventually spiral around and form an accretion disc of superheated material that swirls around.
Due to their high energy, quasars often outshine the galaxies that host them.
What's new — Scientists hunt for these ancient beasts as they inform them of the conditions of the early universe, and how galaxies formed and evolved over time. Additionally, quasars can also help scientists better understand the relationship between galaxies and the black holes at their center.
A team of scientists from the University of Arizona was able to detect the most distant quasar ever observed, located 13.03 billion light years away from Earth. This means the quasar existed when the universe was a mere 670 million years old — only five percent of its current age (astronomers believe the universe is 13.8 billion years old).
The quasar, dubbed J0313-1806, is more than ten trillion times as bright as the Sun, and has about one thousand times more energy than the entire Milky Way.
The quasar hosts a supermassive black hole at its center, with the mass of 1.6 billion Suns. Compared to the supermassive black hole at the center of the Milky Way, which is 13.67 million times the mass of the Sun, that's a pretty big boy.
The recent observations also show that the quasar has a stream of super-heated gas flowing out in the form of high-velocity wind from the surroundings of the black hole at a fifth of the speed of light, according to the study.
Here's what we don't know — Scientists are confused by how this supermassive black hole was able to form and grow to such size so early in the universe. In other words, how did it have time to gobble up so much surrounding material in order to reach its massive size?
“Black holes created by the very first massive stars could not have grown this large in only a few hundred million years,” Feige Wang, NASA Hubble fellow at the University of Arizona and lead author of the new paper, said in a statement.
Scientists believe black holes form in the aftermath of the death of a massive star, an explosive supernova, or by feeding off of the first generation of stars that form inside a galaxy. They then continue to grow over time by swallowing material that surrounds them.
The team behind the new study calculated that if the black hole had formed as early as 100 million years after the Big Bang and grew as fast as possible, it would still be around 10,000 solar masses and not the whopping 1.6 billion that it currently boasts.
"This tells you that no matter what you do, the seed of this black hole must have formed by a different mechanism," Xiaohui Fan, associate head of the University of Arizona's department of astronomy, and co-author of the study, said in a statement.
"In this case, one that involves vast quantities of primordial, cold hydrogen gas directly collapsing into a seed black hole."
In addition to being too big for its own good, the black hole is also ingesting the mass equivalent of 25 Suns each year. Scientists believe that supermassive black holes of this size in the early universe are the main reason why ancient galaxies stopped forming stars, with their black holes gobbling up all the gas and other material necessary to birth baby stars.
WHAT'S NEXT — The rather turbulent relationship between black holes and their host galaxies in the early universe gives scientists a rare opportunity to study how galaxies formed and evolved over time, and the effects of their supermassive black holes on their growth.
The researchers are hoping to conduct further observations of this quasar, as well as find more of these quasars in the early universe, following the launch of NASA's James Webb Telescope, currently slated for October 31, 2021.
Abstract: Distant quasars are unique tracers to study the formation of the earliest supermassive black holes (SMBHs) and the history of cosmic reionization. Despite extensive efforts, only two quasars have been found at z≥7.5, due to a combination of their low spatial density and the high contamination rate in quasar selection. We report the discovery of a luminous quasar at z=7.642, J0313−1806, the most distant quasar yet known. This quasar has a bolometric luminosity of 3.6×1013L⊙. Deep spectroscopic observations reveal a SMBH with a mass of (1.6±0.4)×109M⊙ in this quasar. The existence of such a massive SMBH just ∼670 million years after the Big Bang challenges significantly theoretical models of SMBH growth. In addition, the quasar spectrum exhibits strong broad absorption line (BAL) features in CIV and SiIV, with a maximum velocity close to 20% of the speed of light. The relativistic BAL features, combined with a strongly blueshifted CIV emission line, indicate that there is a strong active galactic nucleus (AGN) driven outflow in this system. ALMA observations detect the dust continuum and [CII] emission from the quasar host galaxy, yielding an accurate redshift of 7.6423±0.0013 and suggesting that the quasar is hosted by an intensely star-forming galaxy, with a star formation rate of ∼200 M⊙ yr−1 and a dust mass of ∼7×107 M⊙. Followup observations of this reionization-era BAL quasar will provide a powerful probe of the effects of AGN feedback on the growth of the earliest massive galaxies.