Question: What does a super massive black hole do?

Claire Greenwell answered on 8 Mar 2019: last edited 8 Mar 2019 3:59 pm

A super massive black hole lives at the centre of a galaxy. It absorbs gas and dust from around it – this spins inwards and makes a structure like a big disc, called an “accretion disc”. As this material falls in, it can get very hot, and bright, and sometimes the intense forces at the centre can cause big bright jets of gas to shoot out of the top and bottom. This is why we can see these from so far away – the accretion disc and the jets can sometimes be brighter than all the stars in the rest of the galaxy!

For example, here is a cool picture of a galaxy called Centaurus A, which is one of the best observed examples. The disk is the darker strip round the middle, and the jets go up and down.