When Black Holes Burn Bright
Black holes are always – black. They have such high gravity’s that any light which enters may never escape. Therefore we may never know what a black hole looks like. This is interesting, if common knowledge. What is not widely known amongst the non-astronomical populace is that Black holes, contrary to popular opinion, can also become some of the brightest objects in the universe.
What happens is this, like our sun a black hole has gravity, in greater amounts I assure you but it is still gravity nonetheless. Now when an object falls towards the sun, say earth for example, if it is going sideways it will still have some momentum and orbit around it. So we on Earth are falling into the sun, just extremely slowly, we have a few billion years before we are in any danger. Anyway this is what happens to things that fall towards black holes.
So any material heading towards black holes tends to orbit around it before falling in. With black holes a great many objects are attracted and they form a massive disk around the black hole called an accretion disk. Think Saturn’s rings but much larger. So most black holes have large accretion disks made of material spinning rapidly around. However speeds vary, much like a hurricane the centre is completely still, but just outside it the wind is at its fastest. so for black holes, the closer you get to the point of no return, known as the event horizon, the faster the material spins.
It also means more collisions, the material closest to the event horizon hits other materials so often that there is a great deal of friction, and with friction comes heat. The hottest parts of the disk can become really hot, millions of degrees hot. Until all of the material heats up into a plasma which forms a second superheated ring inside the accretion disk. This plasma disk, being so hot, is also very bright because when objects heat up they give off light.
That is not all though. Whilst the plasma ring is extremely bright other forces can come into play, it’s all very complex and like everything complicated it involves magnetism. Regardless of how it works a combination of magnetism and other forces send energy to the poles of the disk, and it is a great deal of energy. It actually sends ferocious beams of energy streaming out of both poles. Think of a two laser pointers each the size of several billion suns and you get the idea of the scales involved.
As well as being powerful, they are bright. In fact these kinds of black holes, active black holes, are the brightest continuously emitting objects in the whole universe.
So there you go, the brightest things in the universes are black holes. That greatly confuses and pleases me, the perfect case of not judging a book by its cover.