AQA ยท A level Physics

Early supermassive black hole A-level challenge

Can you get 100%? Use a very early Webb black-hole candidate to test Schwarzschild radius, look-back time and how evidence challenges growth models.

Read about Webb's early massive black hole

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Question

8 marks

Answer all parts. Show your working and give units where appropriate.

1(a)

A black hole has mass 2.0 x 10^38 kg. Calculate its Schwarzschild radius using R_s = 2GM/c^2. Use G = 6.67 x 10^-11 N m^2 kg^-2 and c = 3.00 x 10^8 m s^-1.

[3 marks]

1(b)

Webb detects light that has travelled for billions of years from the host galaxy. Explain why the observation shows the object when the Universe was young rather than as it is now.

[2 marks]

1(c)

The estimated black-hole mass is a large fraction of the estimated stellar mass of its host galaxy. Explain why this challenges a model in which a small stellar seed grows gradually after most of the galaxy forms, and state one observation needed to test the claim.

[3 marks]

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