NASA : Monster Galaxy May Have Been Stirred Up By Black-hole Mischief : Why? Let's Explore!!

Now, how do we know this? Well by looking at the central region of this galaxy the scientists discovered that this bulge that you see right avove in the picture is the largest bulge they've seen of all of the galaxies. In other words the central region of this galaxy is so big that it just doesn't make sense! If there was a central black hole it would not be so big.

But how is it that this galaxy is staying together? How is it even possible for it to not just fly apart? Well, I wanted to take the help of the Universe Sandbox to just discuss with you that a galaxy does not need to have a central black hole to basically stay a galaxy. As a matter of fact, if we were to go back to our own Milky Way and then if we were to imagine basically erasing Sagittarius A* from the center of the Milky Way. What do you think will happen? Do you think the galaxies would actually fly apart and become just a bunch of independent stars?

Now, remember the dark matter is still there. It has actually disappeared and we noticed that it starts kind of increasing the central region. In other words, the central space inside this galaxy starts expanding and this is exactly what we actually observe in A2261-BCG. Now, there was an observation that is very interesting because as central black hole is gone; the central region of the black hole expands dramatically. It becomes a lot less dense and the galaxy itself is also a lot large than it used to be.

Now, it's not a spiral galaxy anymore because there is nothing to orbit around and technically this is actually from a distance at least, an elliptical galaxy and this is kind of what we observe in a lot of galaxies like A2261-BCG. But most elliptical galaxies do have central black holes. But this one even though it's one of the most massive of discovered and one of the biggest we've discovered seems to have nothing. As a matter of fact, compared to our own Milky Way let's just imagine this is A2261-BCG; our own Milky Way would be about ten times smaller. So, it'll be only about 50 times less massive.

Now, there's another simulation of a galaxy we did. This is actually a relatively massive and a large galaxy as well and I just wanted to know what happens if there is a black hole in the middle and then we just kind of remove the dark matter instead and you'll see that galaxies really fall apart pretty quickly without dark matter. Now, in terms of black holes at the center of those galaxies pretty much all of the galaxies we found have them. But many dwarf galaxies and many small galaxies don't have central black holes and by this I mean A2261-BCG is the first large or super massive galaxy that we've seen which has no super massive black hole. Why? That’s actually a good question! Well, so one day we will hopefully discover more of them and one day we will hopefully be able to explain how those black holes actually disappear.

But for now that's really kind of all we know that most galaxies need a supermassive black hole. But don't compulsorily have to have them and we know that even without a supermassive black hole a galaxy can exist just fine and if we were to remove this particular supermassive black hole. Once again if there is no dark matter it kind of just flies apart and becomes really nothing. But however if we were to do the same and just remove the supermassive black hole and actually keep the dark matter in there; it's probably not actually going to fly apart and instead become once again an elliptical galaxy and I guess this kind of goes to show that even though we assume that all galaxies have something really massive in the middle. That something massive doesn't have to be an actual black hole. It can be the actual bulge which itself creates such a huge mass that it's enough for most galaxies to use this as basically the center and the rest of the stars and the rest of the matter just kind of orbits around it and I'm sure Dark Matter also helps as well.