ASTR 622
Observational Cosmology
Problem Set 1
Due Thursday 18 Feb 2002

  1. Derive the age of a flat (Ωm = 1) universe in terms of the Hubble constant H0.
    What is this age if H0 = 72 km/s/Mpc?
    How does this compare to the minimum age of globular clusters, TGC > 11 Gyr?

  2. An important cosmological parameter is the deceleration parameter, defined as
    q = - R (d2R/dt2)(dR/dt)-2.

  3. Using the Friedmann equation (with Λ = 0), show that

  4. Repeat problem 3 including Λ and assuming a flat geometry.

  5. Consider two observers Kang and Kodos at fixed comoving coordinates in an expanding matter dominated FRW universe. A pulse emitted from the location of Kang is observed by Kodos to have redshift z=3. Kodos instantly emits a return pulse in reply. What is the redshift of the return pulse observed by Kang?