Mystery Solved: What Triggers a Sleeping Black Hole's Violent Outbursts at a Galaxy's Center
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July 14, 2011

Mystery Solved: What Triggers a Sleeping Black Hole's Violent Outbursts at a Galaxy's Center

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A new study combining data from ESO's Very Large Telescope and ESA's XMM-Newton X-ray space observatory has turned up a surprise. Most of the huge black holes in the centres of galaxies in the past 11 billion years were not turned on by mergers between galaxies, as had been previously thought.

At the heart of most, if not all, large galaxies lurks a supermassive black hole with a mass millions, or sometimes billions, times greater than that of the Sun. In many galaxies, including our own Milky Way, the central black hole is quiet. But in some galaxies, particularly early on in the history of the Universe, the central monster feasts on material that gives off intense radiation as it falls into the black hole.

One unsolved mystery is where the material comes from to activate a sleeping black hole and trigger violent outbursts at a galaxy's centre, so that it then becomes an active galactic nucleus. Up to now, many astronomers thought that most of these active nuclei were turned on when two galaxies merge or when they pass close to each other and the disrupted material becomes fuel for the central black hole. However, new results indicate that this idea may be wrong for many active galaxies.

Viola Allevato (Max-Planck-Institut fur Plasmaphysik; Excellence Cluster Universe, Garching, Germany) and an international team of scientists from the COSMOS collaboration have now looked in detail at more than 600 of these active galaxies in an extensively studied patch of the sky called the COSMOS field.

The astronomers found that extremely brilliant active nuclei were rare, while the bulk of the active galaxies in the past 11 billion years were only moderately bright. But there was a surprise; the new data showed that the majority of these more common, less bright active galaxies, even looking back far into the past, were not triggered by mergers between galaxies.

The presence of active galactic nuclei is revealed by the X-rays emitted from around the black hole, which were picked up by ESA's XMM-Newton space observatory. These galaxies were subsequently observed using ESO's Very Large Telescope, which was able to measure the distances to the galaxies. When combined, the observations allowed the team to make a three-dimensional map showing where the active galaxies lie.

"It took more than five years, but we were able to provide one of the largest and most complete inventories of active galaxies in the X-ray sky," said Marcella Brusa, one of the authors of the study.

The astronomers could use this new map to find out how the active galaxies were distributed and compare this with predictions from theory. They could also see how the distribution changed as the Universe aged — all the way from about 11 billion years ago to almost the present day.

The team found that active nuclei are mostly found in large massive galaxies with lots of dark matter. This was a surprise and not consistent with the prediction from theory — if most active nuclei were a consequence of mergers and collisions between galaxies it had been expected that they would be found in galaxies with moderate mass (about a trillion times the mass of the Sun). The team found that most active nuclei reside in galaxies with masses about 20 times larger than the value predicted by merger theory.

"These new results give us a new insight into how supermassive black holes start their meals," said Viola Allevato, who is lead author on the new paper. "They indicate that black holes are usually fed by processes within the galaxy itself, such as disc instabilities and starbursts, as opposed to galaxy collisions."

Alexis Finoguenov, who supervised the work, concludes: "Even in the distant past, up to almost 11 billion years ago, galaxy collisions can only account for a small percentage of the moderately bright active galaxies. At that time galaxies were closer together so mergers were expected to be more frequent than in the more recent past, so the new results are all the more surprising."

The image at top of page shows a newly discovered type of AGN (active galactic nuclei) the disk and torus surrounding the black hole are so deeply obscured by gas and dust that no visible light escapes, making them very difficult to detect. Credit: Aurore Simonnet, Sonoma State University.

The Daily Galaxy via ESO

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Comments

Wow, no way man that is jsut WAY too cool.

www.Ultimate-Anonymity.com

What is the picture depicting exactly? Just the nucleus of the Galaxy or is that the whole Galaxy? If it's the whole Galaxy, all the stars in it appear to be immersed in gases, which would not be very conducive to life unless they can withstand a lot of radiation....wow.

Special and, hence, General Relativity forbids infinite density alleged to be at the center of a black hole. Therefore black holes are not only theoretical mathematical entities never observed and never to be observed; they are also an invalid ones.
Besides, Relativity Theory describes a Universe with only one material body in it. But our Universe is clearly doesn't match the description. So it is impossible to describe the alleged black hole at the center of a galaxy using current physics.

WHY then almost every day can one hear about a black hole here or there? These entities have even less validity than souls or minds without a body. Both are undetectable but soul theorists have direct evidence from NDEs, OBEs and such like.

Roman, What are you talking about, I'm interested but do not understand..
Special and, hence, General Relativity forbids infinite density alleged to be at the center of a black hole. Therefore black holes are not only theoretical mathematical entities never observed and never to be observed; they are also an invalid ones.
Besides, Relativity Theory describes a Universe with only one material body in it. But our Universe is clearly doesn't match the description. So it is impossible to describe the alleged black hole at the center of a galaxy using current physics.

It never ceases to amaze me how we can study thing that are so distant from us that we couldn't reach them with the best technology available in our lifetimes!

It never ceases to amaze me how we can study thing that are so distant from us that we couldn't reach them with the best technology available in our lifetimes!

The former Congressman met Amy Petigout and her 3-year-old daughter, Harper, more than a year ago. They've been together ever since. Kennedy said this committed relationship, where they each stand by one another, is a very different world from the one he's known in politics. It’s made him very happy.

2neo:
"Roman, What are you talking about, I'm interested but do not understand.."
Well, you can find more at http://www.sjcrothers.plasmaresources.com/
and non-mathematical summery http://www.sjcrothers.plasmaresources.com/BB.pdf

Fusion and it’s creation at the grandiose scale
Could a black hole’s singularity be so dense that nothing really enters but if contact is made it separates the -/+ particles as well as creating dark matter/dark energy? Which, might explain our expanding universe (e.g. if all of the negative particles showed up like (- - + - + - - + - to infinity). Could this be the reason it would be too dense to actually swallow anything but, instead create the space around us? I would also guess that if the world’s largest hadron collider actually gets turned on & does what is supposed to do, it might create a black hole that would not suck us in but would however be too heavy for our space. Then, it would basically just rip us apart by its massive density like an impenetrable piece of matter expanding from within. The reason that the expansion of the black hole doesn’t envelope everything is that the space it creates stops it from doing so. For example, if somebody tried to hold up an anvil with a sheet of paper it would most certainly break through the paper. As for this anvil it is infinitely dense so it would continue to swell & create the matter around it. I also think that’s why when a supernova happens a black hole is created; to help in the creation of new stars as well as the space for those stars and that is the reason the positive always outweighs the negatives.

Additional Details
*I am saying that upon the primal stages of the black hole’s birth it grabs the closest objects to them thereby destroying them in the process. Now at some point after this it will cease its negative gravitational pull on the surrounding objects at this point in time it will start in the creation of dark matter/ dark energy = positive/MOND. I am definitely not counting out the big bang theory in anyway with this thought.

*This is only a theoretical question for open minded individuals.
*"MOND" (for modified gravity)-push pull effect.
*You can find proof of theses black holes with radio telescopes E.G. the static noise reflected back from space.
* Also see Friedmann-Lemaître-Robertson-Walker metric

“Let the future tell the truth, and evaluate each one according to his work and accomplishments. The present is theirs; the future, for which I have really worked, is mine.”- Nikola Tesla

good post

Fascinating Article.Thanks for sharing.

Mystery Has been solved, good job.


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