Feedback and equilibrium between black holes and galaxies

[Tanelorn]

"The supermassive black hole is sucking interstellar gas, but at the same time it is affecting the star-formation history of the galaxy with its powerful winds," Tombesi said. "Astrophysicists describe this process as a feedback between the central supermassive black hole and the galaxy, which on very long timescales regulates their co-evolution."

http://news.yahoo.com/black-hole-winds-quench-star-formation-entire-galaxies-183105298.htmlI received a warning from someone here about two years ago after asking if control systems theory, feedback, and equilibrium could be at play in situations like the above. So I felt stupid and shut up. Today I learned it is actually thought about in this way. Thanks.

 

[Chalnoth]

Yeah. I think it's largely suspected now that the behavior of the supermassive black hole in the center of a galaxy is largely what determines the galaxy's fate: whether it becomes an elliptical or spiral galaxy.

 

[Tanelorn]

Seems to me that many things in this Universe are based in some way or other on spheres, orbits and equilibrium, now also at the Galactic scale.
I wonder if the next size up will be found to be also..

 

[Chalnoth]

Seems to me that many things in this Universe are based in some way or other on spheres, orbits and equilibrium, now also at the Galactic scale.
I wonder if the next size up will be found to be also..

Well, those are very general terms that don't have a whole lot of meaning. Galaxies are horrifically complicated, and astrophysicists really have a lot to learn when it comes to how galaxies form and evolve.

There really isn't a complete equilibrium, for example. It's more of a pseudo-equilibrium. Galaxies tend towards spiral or elliptical shapes over time depending upon their dust composition, but there are also more complicated configurations such as barred spirals or spirals with a central bulge (which is sort of a hybrid between a spiral and an elliptical).

There are lots of interesting questions here, questions that are really hard to answer. For instance, many physicists think that the rate of star formation determines quite a lot about the future evolution of a galaxy, because a high rate of star formation means lots of supernovae, and supernovae can blast matter away to tremendous distances.

 

[Tanelorn]

Thanks Chalnoth. I agree that galaxies are extremely complicated structures with many different processes affecting their structure and development. I also agree that there is a pseudo equilibrium in place between these many processes bringing stability and order during their evolution.
http://en.wikipedia.org/wiki/Galaxy

Contrast the above structure and order to a possible Universe where stars are distributed everywhere evenly and roam around at random like molecules in a gas.