# Gravitational red shift compared to expansion red shift

From the gravitational red shift: $$\lambda(r)=\lambda(e)\left(1+\frac{gd}{c^2}\right)$$ where $r=received,\,e=emitted$ sources.

Therefore light coming from a distant star to earth would be more red shifted (since $d$ is the star-earth distance which is very large) as compared to the Doppler shift due to universe expansion.

Hubble parameter is calculated using only the Doppler shift: $$z=H_0\frac{d}{c}$$ where $z$ is the red shift parameter.

How is justified this simplification by the gravitational effect?

• someone please answer – Apashanka Das Jul 22 '17 at 14:58