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EXERCISE 6
(NOTE: This exercise is a continuation of Exercise 5.) The quasar LPIF13 produces a flux at Earth's surface of 5 * 10^(-15) Watts per square meter. Quasars typically have about one solar mass (2.0 * 10^30 kg) of matter falling onto their event horizons each year, and convert about 10% of that matter's rest mass energy from gravitational potential energy into luminosity. (a) Using your knowledge of astronomy and reasonable estimates for certain physical values, estimate how far away, in Mpc, the quasar LPIF13 is away from Earth. Remember that 1 Mpc = one million parsecs = 3.1 * 10^22 m. (b) How many times more galaxies than quasars exist in the universe, if the total luminosity from galaxies is roughly ten times the total luminosity from quasars? |