NASA's Spitzer Space Telescope has detected plump black holes where least expected -- skinny galaxies.
Scientists have long held that all galaxies except the slender, bulgeless spirals harbour supermassive black holes at their cores. Furthermore, bulges were thought to be required for black holes to grow.
The new Spitzer observations throw this theory into question.

Read more (http://www.spitzer.caltech.edu/Media/releases/ssc2008-01/release.shtml)

I want to see the astrophysics behind this ... its obviously has to do with rotation of the galaxy and its gravitational field.

It's just the assumed link between a more massive bulge a galaxy has and the bigger the black hole that it contains.
The rare skinny svelte galaxies were thought not to have massive blackholes; but now it seems that they are not galactic freaks. It seems even more likely that supermassive black holes reside inside all galaxies.

Solution = darkmatter

Scientists have uncovered a supermassive black hole at the core of a svelte, spiral galaxy, a finding that questions a recently devised rule of thumb in which only galaxies with bulging cores have such black holes.

Read more (http://www.berkeley.edu/news/media/releases/2003/04/10_skinny.shtml)

Why does it need a bulge to create a SM-BH? It only needs that at some point, the central black hole suck in sufficient material from anywhere. It could have even been the bulge itself which had insufficient rotational speed and collapsed into the BH.

As to the article, if DM exists mostly in the halo of the galaxy, why aren't galaxies "ring doughnut" shaped since light matter will go where the gravity is? And why hasn't all the DM been sucked up by black holes in general rotation since DM does react gravitationally and the large structures it is supposed to form would be ideal for being sucked in as the overall DM structure of a galaxy would be riddled time and again by black holes and so collapse inwards?

Indeed, it seems that a bulge is not needed to create a SM-BH.

if DM exists mostly in the halo of the galaxy, why aren't galaxies "ring doughnut" shaped since light matter will go where the gravity is? And why hasn't all the DM been sucked up by black holes in general rotation since DM does react gravitationally and the large structures it is supposed to form would be ideal for being sucked in as the overall DM structure of a galaxy would be riddled time and again by black holes and so collapse inwards?

What you have discovered is that Darkmatter would have to be fast moving.

The age of the universe is too young for that darkmatter to be slowed down and settled in the centre parts of galaxies. (ie, simply, like the planets haven`t had enough time to spiral into the Sun)

everyone who has seen a galaxy can see that there's always a big sun at the center, not a black hole.

everyone who has seen a galaxy can see that there's always a big sun at the center, not a black hole.

I think that an illusion created by mass of stars towards the center of galaxy

What you have discovered is that Darkmatter would have to be fast moving.

The age of the universe is too young for that darkmatter to be slowed down and settled in the centre parts of galaxies. (ie, simply, like the planets haven`t had enough time to spiral into the Sun)
The Lambda-CDM model, the concordance model, is the model that gives the best fit to observation. The CDM is an abbreviation for Cold Dark Matter, which is slow-moving dark matter. Hot dark matter is fast-moving dark matter, such as neutrinos.
Here is a short excerpt from wiki:
In the cold dark matter theory, structure grows hierarchically, with small objects collapsing first and merging in a continuous hierarchy to form more and more massive objects. In the hot dark matter paradigm, popular in the early eighties, structure does not form hierarchically (bottom-up), but rather forms by fragmentation (top-down), with the largest superclusters forming first in flat pancake-like sheets and subsequently fragmenting into smaller pieces like our galaxy the Milky Way. The predictions of hot dark matter strongly disagree with observations of large-scale structure, whereas the cold dark matter paradigm is in general agreement with the observations.
The two most popular hypothesis' for cold dark matter are WIMPS and MACHOS.
WIMPS are some type of unknown weakly interacting massive particles that cannot be observed by their electromagnetic radiation.
MACHOS are massive, compact halo objects such as black holes, neutron stars, etc.

kaneda,
As to the article, if DM exists mostly in the halo of the galaxy, why aren't galaxies "ring doughnut" shaped since light matter will go where the gravity is? And why hasn't all the DM been sucked up by black holes in general rotation since DM does react gravitationally and the large structures it is supposed to form would be ideal for being sucked in as the overall DM structure of a galaxy would be riddled time and again by black holes and so collapse inwards?
A common misconception is that black holes 'suck in' matter that is around them. Other than very close to the event horizon, the gravity from black holes works like gravity does from any other type of gravitational source. Objects and gas will simply orbit the black hole, unless the velocity of the material is restricted by some mechanism. For example, if were possible for the entire mass of our sun to somehow imploded into a black hole, the orbits of the Earth or any other matter in our solar system would be unaffected.

As to why a galaxy surrounded by a massive halo would not form into a doughnut shape, why does our solar system not form into a doughnut around the sun? Some of out most massive planets ( Jupiter, Saturn, Neptune, Uranus) lie in the outer half of the solar system. By your reckoning, those planets should 'attract' each other and coalease into the doughnut, while the inner planets sould be attracted to the sun, falling into it. I think that is one reason gravity is not described as an attractive force by General Relativity, but instead as a curvature of spacetime that objects of any mass follow the same paths through.

2inquisitive. If most of a galaxy is dark matter and it forms large structures (only), I would think that they do not roam but are fairly stable in their location. Black holes move about the galaxy as does everything else made of "light matter", and suck in whatever gets in their way. That is why they do not run out of material in a few million years. This would include DM which I would think would have to be fairly all pervasive. As large DM structures collapse, they would be replaced by others (with gravity wanting the smallest possible overall structure) which would suffer a similiar fate till there was none left.

As to the solar system, matter is where we see it and seperated by huge distances, beyond the pull of gravity of other planets for the last four and a half billion years. In the galaxy, it is said that most matter is unseen and yet strangely the galaxy is laid out as though there were only light matter in it. So we have several times as much DM as light matter and yet we see no visible effect from all this invisible material. DM reacts gravitationally, so why is it not reacting?

everyone who has seen a galaxy can see that there's always a big sun at the center, not a black hole.

Most of a spiral galaxy's material is in the centre part of the galaxy. Pictures from our telescopes show single stars around the central area. A star the size you suggest is not possible as stars of just thousands of solar masses have very short lives and one you suggest would need billions of solar masses. A (super-massive) black hole is of course not visible by normal means so remains hidden amongst the huge number of stars surrounding it.

The age of the universe is too young for that darkmatter to be slowed down and settled in the centre parts of galaxies. (ie, simply, like the planets haven`t had enough time to spiral into the Sun)

I think the idea is that much of the DM is inside the galaxy, so holding it together as IN THEORY, it has insufficient mass to hold itself together without the DM.

A star the size you suggest is not possible as stars of just thousands of solar masses have very short lives and one you suggest would need billions of solar masses.

You can't really know how long a star can live because no one lives long enough to see a star be born and die.

I think the idea is that much of the DM is inside the galaxy, so holding it together as IN THEORY, it has insufficient mass to hold itself together without the DM.

No, i think you are mixing up two separate observations.
(1) The orbiting speeds of stars in galaxies, and (2) galaxy clusters have insufficient mass to hold itself together without the DM.

The reason why DM was thought of, was to address the problem of the fast orbiting speeds of stars in galaxies.
Much of the mass must be outside of the visible galaxy.

You can't really know how long a star can live because no one lives long enough to see a star be born and die.

Hum,
So we don`t know how long a tree can live to?

Have a quck look at a Hertsprung-Russell (HR) Diagram.

http://en.wikipedia.org/wiki/Hertzsprung-Russell_diagram