Radial velocity/magnitude/luminosity

[YEAH!]

Homework Statement

The spectrum of a quasar with a redshift of 0.20 contains two sets of absorption lines, redshifted by 0.15 and 0.155, respectively. If h0 = 70 km/s/Mpc, estimate the distance between the intervening galaxies responsible for the two sets of lines.

Homework Equations

H₀= 70 km/s/Mpc

 

[zhermes]

Cool. So, where might you start? What does the redshift tell you? What equation involves the redshift?