Question

(c) The following galaxies have had their redshifts measured, and from those, their recession velocities inferred. Using the formulas introduced in the above lesson (under the heading A Shortcut to Galaxy Distances), complete the following table. Assume H 70 km/(s/Mpc). Distance d (Mpc) Redshift z Galaxy Velocity v (km/s) 0.0046 NGC 1326 1,370 NGC 2410 4,600 65.7 NGC 3506 0.021

Answer 1

The formulae used in the solution are the standard formulae used in every textbook. The solution is attached below.

LILLLL L LLL Hubble's law is given as : Ve Hd D = recession velocity H = Hubble's constant d - distance to galaxy The expression which relates redshift and recession velocity isis Z= Z = redshift U = dece ssion velocity C = speed of light for NGC 1326 Z = 0.0046 U - 1370 km/s d = ? U = Hd = d = 0 = 1370 km/s 70 km/s/ MPC (d = 19.57 Mpc for NGC 2410 0 = 4,600 km/s d= 65.7 MPC . Z = 4600 km/s 3x 105 km/s Z= 0.0153 for NGC 3506 Z = 0.021 • 2 = 0 + 0 = zc = (0.021)(3x105 km/s) 0 = 6300 km/s V 6300 km/s = 90 MPC => [d = 9o MPC H 70 KM5I MPC TOINTI

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