A team of astronomers led by the University of Arizona has observed a luminous quasar 1
In addition to being the most distant – and by far the earliest – quasar known, the object is the first of its kind to show signs of an outflowing wind of superheated gas escaping from the surroundings of the black hole at one-fifth the speed of light . In addition to revealing a strong quasar-driven wind, the new observations also show intense star-forming activity in the host galaxy, where the quasar, formally designated J0313-1806, is located.
The researchers will present their findings, which have been accepted for publication in Astrophysical journal letters, during a press conference and a scientific discussion at the 237th meeting of the American Astronomical Society, which will be held almost January 11-15.
The former record holder among quasars in the infant universe was discovered three years ago. The UArizona team also contributed to this discovery. It is believed that quasars originate from supermassive black holes that collect ambient matter, such as gas or even whole stars, resulting in a maelstrom of overheated matter known as an accretion disk that swirls around the black hole. Due to the enormous energies involved, quasars are among the brightest sources in the cosmos, often exceeding their host galaxies.
Although J0313-1806 is only 20 million light-years further away than the previous record holder, the new quasar contains a supermassive black hole twice as heavy. This marks a significant advance in cosmology as it places the strongest constraint yet on the formation of black holes in the early universe.
“This is the earliest evidence of how a supermassive black hole affects its host galaxy around it,” said the paper’s lead author Feige Wang, a Hubble Fellow at UArizonas Steward Observatory. “From observations of smaller distant galaxies, we know this is going to happen, but we’ve never seen it happen so early in the universe.”
Quasars that already collected millions, if not billions, of solar masses in their black holes at a time when the universe was very young pose a challenge to scientists trying to explain how they came to be when they barely had time for it. A widely accepted explanation for the formation of a black hole involves a star that explodes like a supernova at the end of its life and collapses into a black hole. When such black holes fuse over time, they can – theoretically – grow into supermassive black holes. But just as it would take many lifetimes to build a pension fund by cutting a dollar each year, quasars in the early universe are a bit like small millionaires; they must have acquired their mass in other ways.
The newly discovered quasar provides a new benchmark by excluding two current models for how supermassive black holes are formed in such short time scales. In the first model, massive stars, largely composed of hydrogen and lacking most of the other elements that make up later stars, including metals, constitute the first generation of stars in a young galaxy and provide food for the growing black hole. The second model involves dense star clusters that collapse into a massive black hole right from the start.
However, the Quasar J0313-1806 boasts a black hole that is too massive to be explained by the above scenarios, according to the team that discovered it. The team calculated that if the black hole in the center formed as early as 100 million years after the Big Bang and grew as fast as possible, it would still have had to have at least 10,000 solar masses to begin with.
“This tells you that no matter what you do, the seed for this black hole must be formed by a different mechanism,” said co-author Xiaohui Fan, regent professor and associate head of the UArizona Department of Astronomy. “In this case, one involving large amounts of clock, cold hydrogen gas that directly collapses into a black black hole.”
Because this mechanism does not require full stars as a raw material, it is the only one that allows the supermassive black hole in quasar J0313-1806 to grow to 1.6 billion solar masses at such an early time in the universe. That’s what makes the new record quasar so valuable, Fan explained.
“Once you go for lower redshift, all models could explain the existence of the less distant and less massive quasars,” he said. “For the black hole to grow to the size we see with J0313-1806, it would have to start with a black hole of at least 10,000 solar masses, and that would only be possible in the direct collapse scenario.”
The newly discovered quasar seems to provide a rare insight into the life of a galaxy at the dawn of the universe, as many of the galaxy-forming processes that have since slowed down or ceased in galaxies that have existed much longer were still in full swing.
According to current models of galaxy evolution, supermassive black holes growing in their centers may be the main reason why galaxies eventually stop creating new stars. Acting as a fan lamp of cosmic proportions, quasars blast their surroundings violently and effectively sweep their host galaxy clean of much of the cold gas that serves as the raw material from which the stars are formed.
“We think these supermassive black holes were the reason many of the large galaxies stopped forming stars at some point,” Fan said. “We observe this ‘extinction’ at lower redshifts, but until now we did not know how early this process began in the history of the universe. This quasar is the earliest evidence that extinction may have taken place very early.”
By measuring the brightness of the quasar, Wang’s team calculated that the supermassive black hole in the center occupies an average mass equivalent of 25 suns each year, which is thought to be the main reason for its high-velocity hot plasma wind blowing into the galaxy around it at relativistic speed. By comparison, the black hole in the middle of the Milky Way has fallen asleep.
And while the Milky Way forms stars at the leisurely pace of about one solar mass each year, J0313-1806 emits 200 solar masses in the same time period.
“This is a relatively high rate of star formation similar to that observed in other quasars of the same age, and it tells us that the host galaxy is growing very fast,” Wang said.
“These quasars are probably still in the process of building their supermassive black holes,” Fan added. “Over time, the outflow of the quasar heats and pushes all the gas out of the galaxy, and then the black hole has nothing left to eat anymore and stops growing. This is proof of how these earliest massive galaxies and their quasars are growing.”
Researchers expect to find a few more quasars from the same time period, including potential new record-breakers, said Jinyi Yang, the other author of the report, who is a Peter A. Strittmatter fellow at the Steward Observatory. Yang and Fan observed at 6.5 meters the Magellan Baade telescope Las Campanas Observatory in Chile on the night J0313-1806 was discovered.
“Our quasar study covers a very wide field so we can scan almost half of the sky,” Yang said. “We have selected several candidates who we will follow up with more detailed observations.”
The scientists hope to uncover more about the secrets of the quasar with future observations, especially with NASA’s James Webb space telescope, which is currently slated for launch in 2021.
“With terrestrial telescopes, we can only see one point source,” Wang said. “Future observations could allow the quasar to be solved in more detail, show the structure of its outflow and how far the wind extends into its galaxy, and it would give us a much better idea of its evolutionary phase.”
Galaxy survives the black hole party – so far
“The Farthest Quasar in the Universe,” Feige Wang, , Jan. 12, 4: 10-4: 20 EST. aas.org/meetings/aas237
A luminous quasar at Redshift 7,642, arXiv: 2101.03179 [astro-ph.GA] arxiv.org/abs/2101.03179
Provided by the University of Arizona
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