Astro 155							Spring 1989


Homework #2	*	*	*	*	Due on Thursday, April 20

No team work on this one, unles really, really necessary (tsk, tsk).



Determine the ultimate fate of the universe, and while at that, measure 
the rate of galaxy evolution.  In 3 easy steps - here's how:

In CTARGO::DUB1:[JASON] and DEIMOS::MNT:[JASON] you will find file KBAND.DATA,
containing a list of redshifts and K-band magnitudes of an almost complete
sample of distant radio galaxies.  This is the real stuff.

1.  Assume that the data do not need any aperture corrections.  Assume that 
    you are sampling the RJ part of the spectrum at all redshifts.  Assume 
    that there are no important selection effects.  Give all points an equal 
    weight.  Construct the K-corrected Hubble diagram (m vs. z).

2.  Assuming that there is no evolution, and that the cosmological constant
    is = 0, measure the Omega_0.

3.  Now pick your favorite value of the Omega_0, and parametrize galactic
    luminosity evolution as:  L(z) = L(0) * (1+z)**alpha .  Determine alpha.

Then, discuss and criticize your work on all points and steps above.  Be 
quantitative and try to estimate the errors of your ways and measurements.

If you need a computer acct., I'll get you one.  Hubble be with you.