Astronomers have detected a supermassive black hole throwing a galactic-scale tantrum as it feeds, figuratively “turning the table” and cutting off the gas supply its host galaxy needs to birth stars.
The table’s flipping behavior clearly comes in the form of an ultrafast wind emanating from the gently pulsating supermassive black hole located in an average galaxy. The galaxy is named Markarian 817 (Mrk 817) and is located 430 million light-years away in the constellation Draco; The current situation was detected by the European Space Agency’s (ESA) XMM-Newton space telescope.
Supermassive black holes, with masses millions or even billions of times that of the Sun, are thought to be at the heart of all galaxies. But in some cases, these cosmic giants are surrounded by disks of gas and dust called “accretion disks” that “feed” them.
When this is the case, the immense gravity of black holes superheats gaseous and dusty matter, causing it to glow. Additionally, strong magnetic fields direct matter that does not fall into the black hole towards its poles, where the matter explodes at near-light speeds. As a result of this turbulent activity, these regions, known as “active galactic nuclei” or AGNs, can often outshine the combined light of every star in the galaxies around them.
Relating to: Astronomers witness 18 greedy black holes tearing apart and devouring stars
In some cases, AGN-powered supermassive black holes exhibit even harsher behavior; It turns the entire cosmic dinner table upside down by shooting gas from the surrounding accretion disks outward in all directions. This results in “ultrafast black hole winds.”
When this happens, the nervy black hole not only deprives itself of gas to feed on, but also pushes the gas away from its host galaxy, halting star birth across a wide region.
Previously, astronomers had only seen these ultrafast black hole winds coming from extremely bright AGNs that were vigorously feeding the black holes.
“This is the first time we have seen ultrafast winds ejected from the active galactic nucleus (AGN) disk around a supermassive black hole growing at a much lower rate than we expected the activation of such winds.” Elias Kammoun, team member and postdoctoral researcher at Sapienza University of Rome, told Space.com:
Kammoun said that before this discovery, it was widely accepted that ultrafast winds only occurred in parts of the supermassive black hole where gas was spiraling down at very high speeds.
“A large amount of energy is released and radiated in this regime, which is an important factor in driving disk winds,” he continued. “A lot of evidence has shown that the activity of central black holes plays an important role in reshaping the host galaxy and influencing its evolution, which we call the AGN feedback. But the conditions under which this feedback can be triggered are still not very clear.
“Discovering ultrafast winds in a moderately accretive source will enable us to rethink the way we perceive winds in AGNs.”
The black hole fell silent without knocking over the table
Mrk 817 tipped off astronomers that something dramatic was on the horizon when its AGN became extremely quiet. Normally you would expect it to emit high energy light such as X-rays.
Miranda Zak, a graduate student at the University of Michigan and leader of the team, first noticed the strange outage at NASA’s Swift observatory, then followed up with the more sensitive XMM-Newton. Ultimately, Zak found that ultrafast winds from the accretion disk at the heart of Mrk 817 absorb X-rays, effectively hiding signals emanating from the central supermassive black hole.
Later, further analysis of the X-rays from this AGN showed that the central region of Mrk 817 was not just spewing a single stream of gas, but was blowing a massive storm across the accretion disk. And from their observations they can see that it still is. These winds can last several hundred days and consist of at least three different components, each moving at a fraction of the speed of light.
“The identification of disk winds in supermassive black holes accreting at normal rates, such as Bay 817, was never expected,” Kammoun said. said. “The high accretion rate phase is supposed to be a short phase in the life of the supermassive black hole. On the contrary, Mrk 817’s accretion phase can last much longer, thanks to its moderate speed.”
This has two important implications for our understanding of what fuels supermassive black holes, as well as the AGNs they power, he added.
First, this means that even slightly fueled supermassive black holes can expel winds strong enough to reshape host galaxies; they also appear to have long enough lifespans to allow such actions.
Second, if extremely fast winds can emerge from regions around moderately large black holes, then such winds would probably be more common than astronomers currently suspect. Therefore, scientists believe that these winds likely shaped many different galaxies; Some of these we are already aware of.
Related Stories:
— Black hole announces itself to astronomers by violently tearing apart a star
– Record breaker! Newly discovered black hole is the closest known black hole to Earth
— NASA X-ray observatory reveals how black holes swallow stars and eject matter
The discovery that winds from a quiet black hole persist for long periods of time may also one day help answer an interesting question: Why do some galaxies with quiet, gently feeding black holes, such as the Milky Way, appear to have large, vast regions containing stars at their hearts? Does it occur only in very low numbers?
“There is still much to learn, especially about Mrk 817 and the broader winds of AGN,” Kammoun said. “This discovery changes the way we look at AGNs. It will be crucial to know how many of the moderately accumulating sources actually initiate wind. This will help us better understand how common they may be.”
“I believe this is just the tip of the iceberg!”
The team’s research was published Thursday, February 1, in the Astrophysical Journal.