Selections from the following questions will compose ~70% of your final.
Answers must
demonstrate an understanding of the underlying physical concepts.
Also included in your exam will be 2-3 problems based on homework and
classwork.
Observational Measurements (1 question)
OM1. Discuss two types of observations that may be used
to determine star formation rates in galaxies. Explain why each
observation indicates star formation and the limitations of each
in determining the overall star formation rate of a galaxy.
OM2. Explain the effects of dust particles in the interstellar medium
on light propagating through the galaxy.
OM3. What wavelength observations are used to trace neutral
hydrogen gas, molecular gas, dust, ionized gas, and intracluster medium gas?
Explain why each wavelength is appropriate for the corresponding
component.
Galaxy Anatomy and Properties (2 questions)
G1. Describe the main phases of gas in spiral galaxies
and where each component is typically found.
G2. Describe the two types of spiral structure and the possible
origins of each. Discuss the "Winding Dilemma" and how it is addressed in theories
of spiral structure.
G3. Sketch a luminosity function for galaxies and explain what
its shape indicates about the numbers of galaxies as a function of
their luminosity. What kinds of galaxies are most common?
Indicate approximately where the Milky Way would fall
on your sketch.
G4. List and discuss at least three observations that indicate the
supermassive black hole nature of an active galactic nucleus.
G5. Describe the Unified AGN Model and how it explains the variety
of types of AGN galaxies that we see. How does this model connect with
galaxies without AGN?
G6. Summarize the main properties of the different types
of dwarf galaxies,
including their gas content, star formation activity, and
metallicity. How might dwarf galaxies of different
types be linked?
Dark Matter (1 question)
DM1. Discuss the observational evidence for dark matter in
galaxies. Outline the ways that
the mass of a galaxy can be estimated. Can the total mass of a galaxy
be determined, based on available observations?
DM2. Discuss the relative distributions of light and dark matter
in a spirl galaxy. Explain how the relative distributions are deduced.
DM3. What evidence is there for dark matter on group and
cluster scales? Outline how the total mass of a cluster may be
estimated. Does the dark matter in individual galaxies account for
dark matter expected in groups and clusters?
Star Formation and Galaxy Evolution (2 questions)
SF1. What physical characteristics of a gas cloud determine its Jeans
mass? Does the Jeans mass remain constant as a Giant Molecular Cloud
collapses? What does the answer indicate about the formation of stars?
SF2. What is the initial mass function? Why is it important in the
study of galaxy evolution? Give an example of a calculation or model
that requires knowledge of the initial mass function.
SF3. Compare average star formation histories of elliptical, spiral, and
dwarf galaxies. Include in your answer a few representative sketches of the star formation
activity as a function of time for each type of galaxy. How can an
approximate star formation history be determined from a galaxy spectrum?
SF4. Describe the evolution of a galaxy in terms of its stellar and gas
content and its metal abundance. Schematically indicate how galaxy
evolution progresses. What input and output mechanisms may affect its evolution?
SF5. What is meant by the top-down (or monolithic) and bottom-up models
(or hierachical) of galaxy formation?
Give an example of why the hierachical model seems a better fit
to galaxy properties.
SF6. What is meant by "Morphology-Density Relationship"? How might
a morphology-density relationship originate?
SF7. What is meant by "galaxy downsizing"? How does this concept
connect with the star formation history of the Universe? How is it demonstrated
in a color-magnitude diagram?
Galaxy Interactions and Environments (1 question)
CL1. What dynamical timescales are used to estimate the
evolutionary state of galaxy environments? List each and explain.
CL2. Summarize the environments in which galaxies can be found. List
the types of structures in order of increasing numbers and galaxy
density. Identify the structures within which the Milky Way is found.
CL3. How is the intracluster medium detected? What are the properties
of the intracluster medium? What is the importance of the intracluster
medium in terms of mass estimates of clusters? What is its importance
in explaining galaxy evolution in clusters of galaxies?
CL4. What effects do tidal interactions have on galaxies? Under what
circumstances do you expect a tidal interaction to result in a merger?
Last updated: March 7, 2019