The more we study the Universe, the more likely it is that each galaxy revolves around a cosmic colossus – a supermassive black hole that drives the galactic core.
There’s a lot we do not know about these giant objects – including the striking question of how they grow so large – but new research can help us fill in some gaps. According to a new radio recording of all the galaxies in the sky, each supermassive black hole devours in a galactic core matter, though it goes a little differently.
“We are getting more and more indications that all galaxies have huge massive black holes in their centers. This must of course have grown to their current mass,” said astronomer Peter Barthel of the University of Groningen in the Netherlands.
“It seems that thanks to our observations, we have these growth processes in mind and are slowly but surely beginning to understand them.”
There is a funny gap in the mass series of black holes which means we are missing an important piece of the puzzle of how supermassive black holes form and grow. Stars massage black holes – one formed from the collapsed core of a massive star – were detected only up to 142 times the mass of the sun, and even one was heavier than usual, the result of a collision between two smaller black holes .
Supermassive black holes, on the other hand, are usually between a few million and billions of solar masses. You would think that if there were supermassive black holes growing from stellar masses, there would be many intermediate masses, but very few detections were made.
One way we can try to figure this out is to study the black holes we study. has detect, to see if their behavior can give us any clues; this is what a team of astronomers led by Jack Radcliffe of the University of Pretoria in South Africa did.
Their focus was an area of space known as GOODS-North, located in the constellation of Ursa Major. This region, the subject of a deep aerial survey of Hubble, has been well studied, but mainly in optical, ultraviolet and infrared wavelengths.
A portion of GOODS North, each with a galaxy. (NASA / ESA / G. Illingworth / P. Oesch / R. Bouwens and I. Labbé, and the Science Team)
Radcliffe and his team conducted analyzes of the region using a series of wavelengths up to and including X-rays, and added radio observations with very long base interferometry to the mixture. Thus, they identified active galactic nuclei – those containing an active supermassive black hole – that were bright at different wavelengths.
As supermassive black holes actively collect material – which releases gas and dust from their surrounding space – the material becomes hot and glows with bright enough electromagnetic radiation to be seen over large cosmic distances.
Depending on how much dust the galactic nucleus obscures, some wavelengths of this light may be stronger, so no single wavelength range can be used to identify all active galactic nuclei in a sky.
Equipped with this additional information, the team conducted a study of the AGN in GOODS-North and made several observations.
The first was that not all active growth is the same. This may seem like a problem, and we have certainly observed different supermassive black holes increasing at different speeds, but the data is still useful. The researchers found that some active supermassive black holes devour material faster than others, and others do not devour much at all.
They then investigated the presence of starburst activity – that is, a region and period of intense star formation – that coincided with an active galactic nucleus.
It is thought that feedback from an active galactic nucleus can extinguish the formation of the star by blowing away all the material that the stars consist of, but some studies have shown that the opposite can also happen – that material that is shocked and compressed through feedback, can collapse into baby stars.
They found that some galaxies have asterisk activity, and others do not. Interestingly, continuous star activity may make it more difficult to see an active galactic nucleus, suggesting that more research needs to be done to better define the role of feedback in quenching.
Finally, they studied the relativistic jets that can shoot from the poles of a supermassive black hole during active growth. These rays are thought to consist of a small fraction of material drawn along magnetic field lines from the inner region of the growth disk to the poles of the black hole where they are blown into space in the form of rays of ionized plasma, with velocities a significant percentage of the speed of light.
We do not quite know how and why these jets form, and the team’s research suggests that the accumulation of material does not play a major role. They found that radiators sometimes just form, and that either a black hole eats fast or matters slowly.
According to these researchers, this information can better understand the growth behavior and growth of supermassive black holes. And according to them, it also shows that radio astronomy can play a more important role in these studies in the future.
What does it mean that in the future we will have a more powerful set of tools to try to unravel one of the most confusing black hole puzzles – where the supermassive chonkers even come from?
The team’s research was published and accepted in two papers in 2008 Astronomy & Astrophysics. They can be found here and here.