Note: "Information sources"
should be either refereed journal articles or research-grade books.
Wikipedia, SEDS, and non-technical textbooks or popular books do not
qualify.
1. Overdensities
Calculate the overdensity (delta) of the following:
the globular cluster M13
the Milky Way galaxy
the Coma Cluster
the Bootes void
In each case, explain your reasoning, describe whether (and why)
your number is an upper limit, a lower limit, or reasonably close, and
detail your information sources.
2. Growth of Structure
We are going to look at the growth
of
structure in simulations with differing cosmological parameters. The
simulations are the "Hubble Volume Simulations" and more information
can be found at http://www.mpa-garching.mpg.de/Virgo/hubble.html.
I have grabbed the cluster catalogs from two simulations: LCDM and tauCDM.
A description of these files can be found here --
look under "Cluster Catalog Files".
Make a plot of the number of clusters as a function of z in the two
simulations, as well as the ratio N(z|LCDM)/N(z|tauCDM). Describe why
the shapes of the plots look like they do.
Repeat the calculation just for the most massive clusters -- those with
velocity dispersions > 600 km/s. Comment on any differences you see
from the first plot.
3. Collapse of overdensities
Remember our discussion about the
turnaround and collapse of initial overdensities in matter-only
universes. If you have a little overdense bubble of the universe
embedded in a flat universe, show that the density of the overdensity
at maximum size is given by
where the "prime" mark means the
value
of Omega0 in the overdense bubble.
4. Baryon Budgeting
Use the literature to get
estimates of the following for the Coma cluster:
Total mass
Mass of X-ray emitting gas
Mass of stars
From this calculate a local value of the baryon/dark matter ratio
in Coma. Then figure out what you would expect cosmologically given our
discussions of OmegaB and OmegaM. Do these two
numbers match? If not, give some physical reasons why they might not
match.
Graduate Students -- this piece due 11/23.
I want a quality draft
of your project writeup -- the writeup should be 8-10 pages (single
spaced), not including figures, references, and equations.
Oral in-class presentations (25 mins) will be done the last day of
class (Dec 1), and the final writeup will be due Dec
9. The draft due on the 27th of November is to ensure your project is
on track, that you haven't missed any critical details, and that your
emphasis is appropriate for your oral presentation.
