posted on Jun, 13 2010 @ 09:50 PM
Originally posted by Maddogkull
An active galactic nucleus is what is in the centre of the galaxy. Supposedly the amount of EM/luminance that comes from the super massive black hole
is caused by accretion? What is this, if someone can explain it in laymen’s terms. Like how can a black hole give off that much light ???
As material spirals inward toward the black hole, gravitational forces compress the material in a tighter and tighter space. As the material gets
compressed, it gets hotter and hotter, and releases all types of EM spectrum radiation, depending on the gravitational force. In the case of a black
hole, you typically get the x-rays and gamma rays, which are the most energetic wave forms of EM radiation.
The relative luminance of this EM energy being released is much more than in stars or any other part of the galaxy.
To give an analogy that does not accurately describe bathtub physics nor black hole physics, but merely a method for you to attempt to understand
Think of a bathtub. The water in the bathtub is space time. Inside the water of the bathtub, you have various millions of particles floating around
that represent matter. Now, imagine that somebody just opened up the drain!
The drain will be our black hole. Space time and the particles in it begin to flow toward, and spiral inward toward the drain of the tub - a single
point, as this happens, the particles begin to converge into each others paths in the water, begin to get closer together and eventually start to get
in each others spaces, and compress together generating heat which is nothing other than radiation.
If you looked at it in IR, you might see that the drain region was shown to be "hotter" than the surrounding water. As more and more matter is
compressed, or accreted, generating a sustained accretion disk in this way, you'll start to see x-rays and perhaps gamma rays being released from the
accretion area due to the concentration of mass in this area that is more readily compressed by gravitation forces.