Why again do black holes in the center of galaxies have a cloud of light around them?

Question

I used to think it was because of nearby stars where pulled toward the BHs (but not swallowed) but I'm not sure if I buy that idea completely.

does anyone else have other possibilities in mind?

Answer 1

Stuff gets pulled towards a black hole from every which direction.  The means some of the stuff goes straight in but some stuff ends up spiraling down and some stuff ends up orbitting.  Because of the intense gravity, this stuff all ends up going VERY fast.  With all this matter going different directions at different speeds a lot of it collides.  So the answer to your questions - friction makes heat which makes it glow.

Answer 2

as gasses are pulled into it it forms an accretion disk and all of the friction from the swirling gasses swirling very fast around each other makes it light up

Answer 3

matter is heated up to extreme temps when being pulled in by the black hole creating a bright accretion disc. The only reason why anything lights up is because matter releasing energy.

Answer 4

it's from the dust they're sucking in, as it spins around at ferocious speeds around the black hole it gets SUPER heated, and some of the matter being sucked in is actually burned off, rather then just sucked in.

Answer 5

Think of it as a tornado, A tornado is visible because its incredible suction of anything around it for example mud, debris, or trees creates that shape around it. Its like a blender of destruction. Black holes on a larger scale function the same way but it is invisible where the suction occurs and visible to where its powerful gravitational pull gradually sucks everything in its path creating clouds of light and dust.

Answer 6

The science of the "cloud of light" is very clear.

As matter spirals in towards a black hole, it speeds up.  The closer to the event horizon it gets, the density increases (less space around the black hole than farther out) and the faster it moves.

This creates an incredible amount of heat in that material - so much that it actually emits xrays and gamma rays, as well as visible light.

Answer 7

Hi Merc -

The effects discussed above result in very local effects that produce things like synchrotron radiation and fast-moving stars orbiting the black hole itself. However, when you look at distant galaxies, you generally see a central bulge of stars and dust that creates a significant central light cloud. The question in my mind is - what came first - the black hole or the galaxy? If it was the black hole, then the BH may be the gravitational driver for the entire shape of the galaxy, including the twisted shapes of spiral galaxies. If the black hole resulted from the galaxy (as I suspect) then the central bulge is caused by gravitational attraction, and the black hole is just the final result at the very center. But I think the relative brightness is due to the relatively large number of stars that inhabit the central regions due to either gravitational attraction of the other stars or the black hole itself.

ADDED: I'm not sure whether you are referring to a local effect or a large-scale effect. On a local scale, the cloud of light that you are thinking of may be an artist's concept. I've seen a lot of drawings of black holes that show spectacular ring patterns and synchrotron jets. But I have also seen photographs of what they believe to be the black hole region at the center of our galaxy, and the only thing that can be seen is a few stars orbiting it very quickly. The black hole itself is invisible, and there is no light cloud directly associated with it.

Answer 8

Hey Dude,

What's poppin???I hope all is well....

You must keep in mind that due to the large absorption and source confusion when trying to look into the center of a galaxy, it is very, very hard to see what's there! So we have to be clever about the observations we make and the interpretations of these observations. This is one reason that X-rays and gamma-rays are powerful probes in trying to answer such questions; they are much more likely to "get out" of the central region of the galaxy than other wavelengths. Many stars are observed to be in binary systems, where two stars are orbiting each other (as the Earth orbits the sun). Another thing to know is that, the more massive a star is the faster it uses up its nuclear fuel (mostly hydrogen); therefore the sooner it "dies". If we happen to have a binary star system, and the more massive of the two stars explodes as a supernova and it leaves behind a neutron star or a black hole, then it will result in a binary star system with a normal star and a compact object orbiting each other. All these things working out is rare, but there are over a billion stars in the galaxy, so even rare things happen fairly often. Now, imagine that the "normal star" then runs out of its fuel. The first thing it will do is expand as it enters its "red giant phase", as our Sun will about 4,000,000,000 years from now. Then, some of the star's outer atmosphere will spill over onto the black hole. It will eventually fall in, and in the process become very hot. We can observe this hot gas with X-ray telescopes, so we call this an X-ray binary.