Black holes are thought of as agents of chaos, grabbing everything around them and goingbbling it down, a force for destruction on a large scale.
It is unfair, but not entirely untrue. They can also be forces for creation.
They have a lot of appetites and anything that dares to go too close will be gone forever. There is more to it than that. Matter falling in with even a slight sideways velocity will have that amplified hugely as it approaches the black hole and will be like water circling the drain.
An accretion disk is a large, flat circular disk that can be light years across for the largest black holes. The material gets hot and glows. This disk can give a better view of the black holes in the centers of the galaxies.
It can blow matter away from the black hole. This can happen in the form of a subatomic particle wind generated just from the heat of the disk, or complex magnetic fields in the disk and the black hole can create twin vortices, like tornadoes, that pull matter up and away from the disk near its center.
These don't necessarily mean doom. They are not quite clement, with matter screaming out at the speed of light, high-energy gamma and X-rays pouring forth, and the like. There are two ways this can happen. The wind from the colossus can cause star formation near active black holes by collapsing surrounding gas clouds. The black hole outflow can push gas out of the galaxy and cause star formation.
It depends on the situation. The mass of the universe. The gravity of the stars makes it difficult to blow the gas away. It may get blown out, but eventually slows to a stop and falls back in, like in the picture in the right.
Some of the universe are smaller. These dwarf galaxies have black holes in them, but they don't have as much gravity to hold gas in. Does an active black hole in the core of a dwarf galaxy affect star formation?
It's close enough to see details in Henize 2-10, a dwarf galaxy about 30 million light years from us. The core of the galaxy is a mess, clearly disturbed, and emitting 100,000 times the brightness of our Sun in X-rays alone, and that energy is coming from a very compact region just a few light years away. It is similar to the description of a black hole.
It matches the description of a powerful explosion. There is a debate on what is going on in the core. New research shows that it is a black hole. A hallmark of black holes is the variation in X-ray brightness on a timescale. If a black hole were not there, the stars would be around the center of the galaxy at a faster rate than you would expect, and that excess points to a black hole that is 1.5 million times larger than the Sun. The central black hole of the Milky Way is over 4 million solar mass and is considered small.
Why is that important? The conclusion of the new research is that they found a 500-light-year-long filament of material flowing away from the center of the galaxy and into a big cloud of gas that is furiously forming stars.
They found evidence that the gas in the cloud was getting violently slammed by the outflow at high speed, and that it could be coincidence. The stars seem to be forming in a straight line from the outflow, which makes sense if the black hole is slamming into a gas cloud and pushing the gas away. They can see something on the opposite side of the center, though it's not clear if it's from the other jet.
It makes sense that what we are seeing is not a straight jet but one that is precessing, since the outflow follows a pattern of speeding up and slowing along its length. This has been seen in black hole disks before, and can occur if the disk is wobbling around the black hole like a top, pointing the jet in a huge circle that takes 200,000 years to make one cycle. If the infalling material makes the disk at an angle to the black hole spin, or if a recent galaxy merger throws off the disk's angle, that wobble can happen.
There are models of how a black hole-driven jet would slam into a gas cloud. It looks like it is a black hole, it has launching jets, and it is triggering star formation.
It is very cool if this is the case. It is 3000 light years across, so it is fairly low mass. It would be easy for the black hole to blow up material in the universe, but that is not what has been seen. The black hole may not have enough energy to send material into space because it appears to be underluminous.
It looks like the black hole, while sowing some chaos, is also sowing new stars.
I don't know if this will make you see black holes in a different way, but maybe you should give a nod of appreciation in their direction. They make a mess of things, but they also help make stars.
I always like to give it a shout out when I can because I worked on the Hubble camera for several years before and after launch.
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