Astr 328 Final Exam Study Questions
You are interested in studying the structure of an elliptical
galaxy believed to be roughly at the distance of the Virgo cluster, but
need a good distance measurement first. What are the possible techniques,
and which would you choose? Why?
An astronomer claims to have found an interesting evolutionary
effect by studying rich clusters of galaxies at high redshift: spectra
of galaxies at the cluster center show strong emission lines at high
redshift, while those at intermediate redshift have spectra dominated by
absorption lines. How would you interpret these results? Do you see any
problems with them?
Why does the detection of even one cluster with mass 1015
Msun at z=1 constrain Omega_matter?
Why is hydrogen the most common element in the universe?
Why is the detection of a galaxy at z=3 more challenging
than the detection of a QSO at a similar redshift? What are some possible
reasons why high-redshift galaxies have smaller angular diameters than
would be expected from the size of galaxies such as the Milky Way and M31?
Recent work on Type 1A SNe has shown that they are not standard
candles. Describe this result, and give a physical reason for what is observed.
Why do astronomers persist in using them as probes of the geometry of the
Explain how the Sunyayev-Zeldovich effect is used to measure
the Hubble constant, and discuss possible systematic errors.
Why are measurements of deuterium abundance at high redshift
of great interest to cosmologists?
Why do you need a space telescope to estimate the history
of metal production in the universe? Explain how this is done, and why
estimating the star formation history of the universe is a tougher proposition.
What are the advantages of studying the growth of structure
in the universe using QSO absorption lines (in particular, the Lyman alpha
forest) instead of galaxies?
Starting with the Friedman equation derive the following
for an Omega=1, Lambda=0 universe.
the current age of the Universe
Explain the test behind the supernova cosmology project,
and the recent results from this project. What systematic errors could
influence their results?
Why is "standard CDM" (Omega=1, Lambda=0 cosmology) dead?
Give me all the reasons you can think of.
Explain how galaxy clusters can be used to
study dark matter
constrain different cosmological models.
How and why does structure form differently under hot dark
matter and cold dark matter models?
Starting with the differential equation which describes the
evolution of density fluctuations, show that in an Omega=1 universe fluctuations
grow as (1+z)-1.
Why couldn't dark matter be all baryonic?
What is the basic physics used in measuring the mass of a
galaxy cluster using its hot X-ray gas? What observations are needed?
Explain the Lyman break technique and how we use it to identify
high redshift galaxies.
Describe what we mean by "peaks" in the power spectrum of
the microwave background. What causes these peaks, and what do they tell
us about the Universe?
Describe qualitatively how structure grows with time in the
following sets of universes:
Make sure you explain why structure evolves
differently in these different universes. Based on these arguments, and
the observed structure in the universe what value or ranges of values are
acceptable for Omega_lambda and Omega_matter?
Omega_lambda = 0, Omega_matter increasing from 0.1 - 1.0
Omega_matter = 0.3, Omega_lambda increasing from 0.0 - 0.7
Describe how we can use peculiar velocities to measure the
matter content of the Universe? How do we derive those peculiar velocities?
In this context, what is the Great Attractor?
Why do we currently believe that the cosmological constant
is real? Give several lines of evidence.