Astr/Phys 328/428 Final Exam Study Questions (2016 edition)
final exam is Tuesday, December 13th, 8:00am-11:00am. It is closed notes,
no calculators, just you, your brain, a pencil or pen, and a blue book.
It will consist of 5-6 questions
taken from this list. You should plan on spending ~ 2-3 blue book pages
answering each one. Remember to always answer with a "what" (i.e.,
describe the object/effect/concept in question) and a "why" (i.e.
explain physically why it behaves the way it does).
- "several" = "three or more"
- "sketch" = "a plot with labeled axes"
- Describe and sketch the Press-Schecter
relationship for collapsed dark matter halos. Why does it have the
shape it does? How and why does Press-Schecter evolve with redshift?
- Describe the Sunyaev-Zeldovich Effect, and how
can use it to constrain cosmological parameters. What data is needed
for this test?
- Describe Big Bang Nucleosynthesis (BBN).
Observationally, how can we constrain OmegaB from BBN
arguments? What is the best estimate for OmegaB from these
- Describe the physics behind the microwave
background, and explain how the CMB constrains models for structure
formation in the universe.
- Why is "classical standard CDM" cosmology (i.e.,
Give me several well described arguments.
- How and why does structure form differently under
matter and cold dark matter models?
- Observations suggest that OmegaM ~
couldn't the dark matter all be baryonic? Give
several reasons why.
- Explain the Lyman break technique and how we
high redshift galaxies. Describe the properties of Lyman Break Galaxies.
- Describe how the growth of structure is
different (both to z=0 and in the future) under these two cosmologies:
Make sure you explain why
differently in these different universes. Based on these arguments
the observed structure in the universe what value or ranges of values
acceptable for OmegaL and OmegaM? Why?
Explain what is meant by the "Radiation-Dominated Era",
"Matter-Dominated Era", and "Lambda-dominated Era". How does the
expansion of the universe behave during these eras? What determines
when transitions between these eras happen?
- OmegaM = 1.0, OmegaL = 0 (classical standard CDM)
- OmegaM = 0.3, OmegaL
=0.7 (current concordance cosmology)
Describe how we can use peculiar velocities to
matter content of the Universe? How do we derive those peculiar
In this context, what is the Great Attractor?
Why do we currently believe that the
(or "dark energy" in general) is real? Give several lines of evidence.
Describe how globular clusters are age dated, and
how these ages can be used to
constrain cosmological parameters (ie OmegaM, OmegaL,
H0). Be specific!
Describe what the two point correlation function
(2pt CF) measures. How is it parameterized for galaxies, and what is
the meaning of the different parameters? How do observational effects
distort our measurement of the 2pt CF? Describe how different kinds of
galaxies are clustered.
What do we mean by "reionization in the early
universe"? How do we measure this, and at what redshift did it happen?
What are possible sources of this reionization?
Describe several reasons (both physical and
observational) why high redshift
galaxies might look different from galaxies in the local universe.
It is said that in a universe with cold dark
matter (CDM), structure (galaxies and galaxy clusters) grows
hierarchically. Describe this process, and explain why the properties
of CDM mandate that growth must be hierarchical. Describe how
different kinds of galaxies (i.e., spirals and ellipticals) grow with
time -- think about and discuss merger trees. From observational
evidence, why is it said that cluster ellipticals formed at high
redshift (z>2), and why is even that statement
Write down the Friedmann equation and describe
each term. In today's "concordance cosmology" (i.e., using the current
best values of the cosmological parameters), show how the scale factor
of the universe will change with time in the far future (longer than a
few more Hubble times). How will large scale structure evolve in the
universe at these late times, and how will our ability to study large
scale structure change? Describe, in general, the evolution of the
universe of the next 10 Hubble times or so.
This plot shows the joint
constraints on the cosmological parameters OmegaM and OmegaL from three
different techniques: the microwave background (CMB), studies of
supernovae at high redshift (SNe), and measurements of large scale
structure at z~0 (BAO). BAO has the strongest sensitivity to the matter
density parameter, which is why its constraint is mostly vertical.
Describe qualitatively why the other contraints have the shape they do
-- that is, why do the CMB constraints follow a "downward" diagonal,
and the SNe constrains follow an "upward" diagonal?
Why do we need to study relatively distant
galaxies to get a get a measure of the Hubble constant? Why can't we
just use distances to nearby galaxies, where Cepheids give us good
distances, to measure H0? Why are Cepheid distances so important for
Explain how "supernova cosmology" projects work, the cosmological test they make, and the results from these projects.
Explain and compare the two galaxy dynamical
distance indicators discussed in class. What kinds of galaxies do they
work on? What are the advantages and disadvantages to each one?
Describe the star formation history of the universe. How do we measure it? How has it changed with time?
For a OmegaM=1 universe, work out mathematically
how the proper horizon distance changes with time, and solve for its
value (in Gpc) at z=0.
Describe what baryonic acoustic oscillations are, how they evolve, and how we measure their effect observationally.