If the distance of a galaxy at a redshift z = 0.5 is 1,800 Mpc,what is H₀?
A) 3,600 km/s/Mpc
B) 0.0003 km/s/Mpc
C) 83 km/s/Mpc
D) 900 km/s/Mpc

Question

Quizplus · Accepted Answer

The formula to calculate the distance of a galaxy is:
distance = (speed of light) x (redshift) / (H₀)
where H₀ is the Hubble constant.

Given distance = 1,800 Mpc and redshift z = 0.5

So, we have: 
1,800 Mpc = (speed of light) x 0.5 / (H₀)

Therefore, H₀ = (speed of light) x 0.5 / 1,800 Mpc

Using the value of the speed of light as 299,792.458 km/s

H₀ = 299,792.458 x 0.5 / 1,800

H₀ = 83.27 km/s/Mpc

Therefore, the best choice is C: 83 km/s/Mpc.

If the Distance of a Galaxy at a Redshift Z