• Question: Do you agree that there is a super giant black hole at the centre of every galaxy?

    Asked by BrennanW to Heather, Helen, Hugh, Jane, Julian on 16 Nov 2014.
    • Photo: Julian Onions

      Julian Onions answered on 16 Nov 2014:

      Yes – the evidence is pretty good. Following the tracks of the stars near the very centre of the galaxy that have been followed for many years show they are all orbiting something VERY heavy that we can’t see, and is very small. The only thing we know that fits the bill is a very large black hole.

      See the following video which shows the stars going around it.

      We’ve also detected these in other galaxies, so we think all galaxies have them.

    • Photo: Helen Johnson

      Helen Johnson answered on 16 Nov 2014:

      We’re not entirely sure if it’s all galaxies – some might just be too small to have these supermassive black holes – but definitely a large fraction of galaxies yes 🙂 As Julian says, we’ve seen direct evidence that there’s a black hole called Sagittarius A* at the centre of the Milky Way, which weighs the same as about 4 million suns! As well as observing the orbits of stars around this very small yet very dense region of space (so dense it must be a black hole), we’ve seen X ray and radio emission from it, which again confirms the theory.

Comments