In a model of the universe, the Hubble parameter has the following functional form H(z) = H0(1 + z)^(5/4), where H0 is the Hubble constant.
Answer the following questions:
1. Can a spectrograph that operates in the visible region of the electromagnetic spectrum (i.e. 0.38 um to 0.74 um) detect the Hb (H beta) line from a galaxy with a comoving distance D = c/2H0 (c being the speed of light).
2. How long did it take for light to reach an observer, at the present time, from a galaxy that has a redshift z = 2.0? Assume H0 = 67 km/s Mp/c. Express your result in Gyr.