Problem #1: Elliptical galaxy XJS-16 has a spectrum which can be approximated as a 5500 K blackbody.
a) Calculate the wavelength of the peak of this galaxy's spectrum if it's nearby (i.e., redshift = 0).
b) Calculate the wavelength of the peak of this galaxy's spectrum if the galaxy has a redshift of 3.0.
c) If this galaxy has a redshift of 3.0, in what wavelength region (e.g., x-ray, ultraviolet, visible, infrared) is it brightest?
Problem #2: a) Calculate the value of the critical density
for a Hubble constant of 75 km/s/Mpc (Be careful with units! You should come out with an answer in units of kg/m3.)
b) Calculate the density of the visible mass in our Local Group of galaxies, if the Local Group contains about 4 x 1012 solar masses of material within a spherical volume of radius 3 Mpc.
c) If the universe has a density similar to the density you found for the Local Group in part b), is our universe open or closed?