Ok,
I know this has probably been covered, but.

1.All galaxys have black holes at their center.
2. Quasars are baby galaxys.
3. Black holes at the center of each galaxy do not get full as has been theorized. They simply reach homeostasis with their surroundings. They are no different that a star when it comes to their gravatational influence on their surroundings. (Don't give me singularities, event horizons....... we all know the basic laws of phyics are shot to hell once you cross the point of no return)
4. Eventually black holes have consumed all matter not moving at an escape velocity high enough to reach orbit around the blach hole.
5. The pressure of matter consumption (radiation) actually works against the black hole to keep matter...."pushed back form the black hole".
6. Black holes at the center of all Galaxys do feed occasionally due to the errant star, gas cloud, space ship......

Right? :^o

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Not necessarily all, but certainly most, and this does seem to be the current hypothesis.

Quasars have been found to have host galaxies, implying that they are not always stand-alone objects. As much as I'd like to see a theory of galactic evolution start with quasars as the step 1, I don't think we're there yet.

I think this is more or less stating the obvious. The gravitational attraction from a large mass, star or singularity, will continue to pull in matter until it reaches an equilibrium point. Both will continue to add mass as well.

Right....

I'm not too familiar with this process. Do you have any more info on it?

Unless the orbiting bodies are perturbed to such a degree, I would imagine the orbits are mostly stable. But yes, spaceships get caught all the time

Mostly, why? [/i]

.Well every Galaxy that we've look at to find a black hole we have.
.Quasars and host Galaxies? Haven't heard of that, but am sure your right. Following the logic that I used earlier, is it possible that a quasar with a host Galaxy is a quasar caught evolving?
. The pressure thing...working on that.

.Right?= Validate or pick apart.

Thanks for the feedback!

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Not all galaxies have black holes. Large ellipticals and spirals do. Dwarfs (dwarves?) and irregulars do not.

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T. Anderson

Also, aren't quasars just the jets shooting out of black holes? I was under the impression that we see these jets shooting out of fully-formed galaxies (Seyfert galaxies), so I don't see how they could be baby galaxies.

It's possible that they are an early stage in galactic evolution, but it isn't well-researched enough yet.

Right, but this could be an indication that the black hole is a driving force in the evolution of larger galaxies. I've always been inclined to the theory that spiral galaxies are spiral because of the supermassive black hole, and that ellipticals are in more of an equilibrium state with their black hole, hence the lack of rotation. There's no explanation yet (that I know of) for how the black holes got there first, but it's an interesting development.

The spirals are a result of the net residual momentum of the progenitor cloud. Giant ellipticals are the result of mergers, which tends to cancel the rotational momentum of the original galaxies (see Centaurus A for an example of an intermediate stage - an elliptical with the remnants of the disk of one of the progenitor galaxies).

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Right, but why would this rule out the possibility of the black hole's presence giving rise to some net angular momentum in the dust cloud?

I would think this is true in some cases, but not all. I mean we observe many pairs of merging galaxies, and it doesn't seem that they would all settle into ellipticals even after billions of years. Plus elliptical galaxies, IIRC, are much more common than spirals, which would indicate they have form in other ways, not due to collisions or mergers.

A black hole is a point mass (on galactic distance scales). How would the presence (or absence) of a black hole affect angular momentum one way or another?

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

It's a chain reaction effect almost. A black hole (the supermassive ones in the center of galaxies, at least) would provide a gravitational attraction in the intergalactic dust. The presense would be significant enough to provide a centripetal force for much of the floating dust, giving rise to a spinning system. As the central masses begin to coalesce, the entire system (the galaxy) would have a resultant angular momentum, causing it to rotate. I'm not 100% on this, nor am I sure that this is even remotely close to the accepted theory, but it seems plausible.

There may be a selection bias at play here. SMBH tend to be identified in large galaxies, but not in smaller ones (Dwarfs, Irregulars, etc). As a result, if your aim is to find an SMBH, you are likely to target large galaxies to increase your chances of success (there are other reasons as well, such as larger galaxies are accordingly brighter and therefore easier to obtain spectra of the nuclear region, but that is by-the-by). I'm not familiar with any formalised study to even look for SMBHs in small galaxies.

There is a lot of current discussion about the role of black holes in galaxy formation. Jury's still out.

Possibly. It is interesting that quasars are an 'old' phenomenon. IIRC, there are no quasars within a couple of billion lightyears, which may hint at an evolutionary progression. However, it could also just mean that the SMBH's have all run out of fuel.

Are you are familiar with the Standard Models of Active Galactic Nuclei, which posit that Seyferts, BL-Lac objects, quasars, etc are the same type object simply viewed from different angles?

Are you referring to some sort of Eddington-type Limit here?? :-s If so, just off the top of my head I would guess that this might only come into play if the gas were contracted toward the SMBH in a sphere. The angular momentum of the gas settling into the SMBH creates an accretion disc, in which I don't think the Eddington radiation would have much of an impact overall.

Just my $0.02.

Thanks for the feedback![/quote]

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WOW! Great responses all of you. I could really dig a coffee chat with you guys.

It like the fact that just like politics, spirituality, medicine, every aspect in astronomy has different angles, and viewpoints.

I too am confounded by the age of Quasars, but has the definition of a quasar changed?

Ok, so is a Quasar the SUPER HOT GAS emitting radiation and glowing at over 1million deg? Or is it by definition the actual jet of radiation produced by a black hole as atoms are torn apart and throwing radiation in a specific direction. Traditional quasars have both, super hot gas and the radiation plumes don't they??

The dictionary definition of a quasar makes any black hole a quasar during a feeding frenzy.

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