Question: what are the galatic nuclei made up of ?

Jen Gupta answered on 16 Jun 2011:

Good question! We think there is a supermassive black hole in the centre of every galaxy, this black hole can be a billion times the mass of the Sun. Most of these black holes are just sitting there minding their own business but some of them are “active”. We don’t know what makes some of them active and others not but I can tell you what we think is going on in the active ones, even if I can’t always tell you why.

So in active galactic nuclei the supermassive black hole is pulling all of the surrounding material towards it. This forms a disk of material around the black hole that gets heated up and emits the x-rays that we see coming from active galactic nuclei. A bit further out there are clouds of gas that are moving fast because of the gravity of the black hole. This movement stretched out the light they emit and we can detect that. We then think there’s a torus (doughnut shape) of dust around this bit so if the system is at a certain angle, we don’t see the fast moving clouds of gas. A bit further out still we think there are more clouds of gas but because these are further away from the black hole, they move more slowly and the light from these clouds isn’t stretched as much. Somehow jets of material form and are emitted from the poles of the system. We think this has something to do with magnetic fields but we don’t know what! These jets emit the radio waves that we see. There’s a picture on my profile showing a cartoon of what we think active galactic nuclei look like, this might help you to understand what I’ve said 🙂

Please let me know if this doesn’t make sense, I still sometimes find this confusing!