Using the James Webb Space Telescope (JWST), researchers have found the oldest and most distant black hole ever observed as it consumes its host galaxy.
The finding may represent a significant advancement in our knowledge of how supermassive black holes attained masses millions of billions of times greater than the sun during the very early stages of the cosmos.
The black hole is located in the old galaxy GN-z11, which is approximately 400 million years after the Big Bang and is located 13.4 billion light years away. The black hole itself appears to be consuming stuff from its surrounding galaxy at a rate five times faster than what current theories predict is viable, despite being roughly six million times more massive than the sun.
Roberto Maiolino, the team leader and head of the University of Cambridge Department of Physics, called the discovery “a giant leap forward” for the field of black hole study in a statement.
“We have to think of other ways they might form because it’s very early in the universe to see a black hole this massive,” Maiolino stated in the release. “Very early galaxies were extremely gas-rich, so they would have been like a buffet for black holes.”
Do enormous black holes overindulge in food?
Formation theories are challenged by the size of early supermassive black holes that formed when the universe was younger than 1 billion years old, as it should require billions of years of continuous feeding to achieve a mass of millions or billions of times that of the sun.
“It’s like seeing a family walking down the street, and they have two six-foot teenagers, but they also have with them a six-foot tall toddler,” Maynooth University research fellow John Reagan, who was not involved in this research. “That’s a bit of a problem; how did the toddler get so tall? And it’s the same for supermassive black holes in the universe. How did they get so massive so quickly?”
There are now two main theories among scientists regarding how black holes could become supermassive in the early cosmos. They may begin as tiny black hole seeds, formed when enormous stars collapse at the end of their lives, millions or billions of years in the future, or they may bypass this stage completely.
If massive clouds of cold gas and dust collapse, a “heavy black hole seed” with a mass a few million times that of the sun might arise right away. In this manner, the process accelerates through stellar evolution spanning millions or even billions of years, providing an early advantage over the feeding and merger processes that aid in the development of black hole seeds into supermassive black holes. That heavy seed theory is supported by the discovery of this new old black hole, whose mass is a few million times greater than that of the sun.
On the other hand, the rate at which the black hole in GN-z11 is accumulating matter may indicate that black holes have the ability to feed far more quickly than has been recorded for other black holes found in the early universe. This would support the notions of minuscule black hole seeds.
The Eddington limit is a mathematical formula that indicates the maximum mass that a body, such as a star, can acquire before its brightness, or radiation output, pushes that mass away and cuts off its food source.
The material that swirls about black holes is violently stirred and heated by their immense gravitational pull, producing radiation in the process. However, black holes themselves do not produce light because they are surrounded by a light-trapping boundary known as an event horizon. A region known as an active galactic nucleus (AGN) emits light that increases in intensity in direct proportion to the speed at which the black hole feeds.
Therefore, this region is covered by the Eddington limit, which can also work to push material away and stop a black hole’s feeding frenzy.
The pace at which matter is being accreted from its host galaxy by this recently discovered black hole is five times faster than the Eddington limit. Though they happen in brief spurts, periods of so-called “super-Eddington accretion” are possible.
The researchers calculated that the black hole might not have needed to begin as a hefty black hole seed if this period of ravenous feeding had continued for 100 million years. It may have originated from a much smaller stellar-mass black hole seed between 250 million and 370 million years after the Big Bang, and it might have expanded quickly to reach its current mass 13.4 million years ago as observed by the JWST.
Black hole feeding could destroy its host galaxy
The team is quite positive that GN-z11, which is around 100 times smaller and extremely bright than the Milky Way, is the result of strong feeding from this black hole. However, the ravenous black hole is also probably going to impede the expansion of its host galaxy.
Gas and dust are probably being forced out of the center of the galaxy by extremely fast gusts of particles that are belching out from around the feeding black hole. The black hole is “killing” the growth of this little galaxy by putting an end to the formation of stars through the collapse of cold clouds of gas and dust.
The team behind this research thinks that the power of JWST should help uncover more black holes in the early cosmos in addition to providing additional information about this black hole and its galaxy.
In particular, they are aiming to discover small black hole seeds in the infancy of the cosmos and put to bed the debate surrounding the premature growth of supermassive black holes.
“It’s a new era: The giant leap in sensitivity, especially in the infrared, is like upgrading from Galileo’s telescope to a modern telescope overnight,” Maiolino concluded. “Before the JWST came online, I thought maybe the universe isn’t so interesting when you go beyond what we could see with the Hubble Space Telescope. But that hasn’t been the case at all: The universe has been quite generous in what it’s showing us, and this is just the beginning.”
