The Andromeda Galaxy (M31) and the Milky Way are the two largest members of the Local Group. Andromeda is currently moving towards our galaxy at a speed of 110 km s−1110\text{ km s}^{-1}110 km s−1, and the distance between them is approximately 780 kpc780\text{ kpc}780 kpc.
Discuss whether these data can be used to estimate an age for the Universe.
There is a supermassive black hole at the centre of a nearby active galaxy. The mass of this black hole is 3.80×1093.80 \times 10^93.80×109 solar masses.
Calculate the radius of the event horizon of this black hole. State an appropriate unit for your answer. (Take 1 solar mass=1.99×1030 kg1\text{ solar mass} = 1.99 \times 10^{30}\text{ kg}1 solar mass=1.99×1030 kg, G=6.67×10−11 N m2 kg−2G = 6.67 \times 10^{-11}\text{ N m}^2\text{ kg}^{-2}G=6.67×10−11 N m2 kg−2, and c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1.)
Over cosmic timescales, galactic collisions are predicted to trigger quasar activity. Explain what is meant by a quasar, and suggest how a galactic merger can produce a quasar. In your answer you should:
