Do the reading, look at the questions at the end of each chapter for practice and consider the following.
Cosmology
What is Cosmology? What is Cosmogony?
In what sense is cosmology science? What makes a field scientific? In what sense (and when) might it be argued that cosmology moves into philosophy? What are some things which make cosmology a difficult field (what are some things which make cosmology difficult)? What are some ways people view the Universe. Which is correct? In this class, what path to understanding of the Universe do we follow?
There are a few observational facts which drive our thoughts about cosmology; the expansion of the Universe, the existence and properties of the CMBR, the chemical composition of the Universe. Today, we interpret these observations (and some further ones) within the context of what is known as the Big Bang Theory. What are the interprertations of these results?
What are the Cosmological Principles discussed in class? What are the implications of the different principles? Which principle is thought to be correct? Which principle is currently used to drive cosmological theories? How does the notion behind the Copernican revolution influence our interpretation of cosmological data? What are the meanings of the terms homogeneous and isotropic? Give examples which illustrate each property. Why are the matter/anti-matter balance and the smoothness of the CMBR interesting and perplexing results? How do we contend with these things in our current theories? What do you think is the explanation for these results (and other fine-tuning results I will bring up later)?
According to theory and current observations, how old is the Universe? How old are the oldest objects in the Universe? How is the age of the Universe inferred?
There are a few observational facts which drive our thoughts about cosmology; the expansion of the Universe, the existence and properties of the CMBR, the chemical composition of the Universe. Today, we interpret these observations (and some further ones) within the context of what is known as the Big Bang Theory. What are some other observations which help to fill out our understanding of cosmological models (in particular, the Big Bang)?
What is the Cosmological constant?
In what kind of Universe are we thought to live? How can we go about deciding in which type of universe we live? Use the geometry of the different universes to infer properties of parallel lines, the interior angles of triangles, ... . Have we been able to perform tests to look at these different possibilities?
What are the meanings of the terms, open universe, closed universe, and flat universe? What tests may be used to deduce the type of Universe it is in which we live?
Milky Way
The Milky Way is a spiral galaxy. What are the general properties of spiral galaxies and the Milky Way, in particular? There are also other kinds of galaxies among which are included those known as elliptical galaxies Irregular galaxies and S0 (lenticular) galaxies. Overall, what are the properties of typical large galaxies.
The Milky Way (as do all spirals and S0s) has a luminous disk of stars, gas, and dust and a larger more spherical halo. Schematically, what does the Milky Way look like?
Where is the Sun located in the Milky Way galaxy? Where are the bulk of the stars, gas, and dust located? How did we figure these things out? What are globular clusters and why are they useful in this context? What objects trace out the spiral arms in the Milky Way and in other spiral galaxies? What are Population I stars, Population II stars? What is meant by the term Dark Matter? What are the ways we infer the mass of the Milky Way galaxy? What are MACHOs and what are MACHOs used for? What are the properties of the bulge of the Milky Way? What properties of the nucleus of the Milky Way suggest are similar to AGNs?
Tail end of Milky Way Stuff
Roughly, what is the way black holes were defined in class? What is special about the speed of light? How fast is the speed of light? Is there a black hole at the center of the Milky Way galaxy? How could do we deduce that there is a black hole at the center of our Galaxy? For what would we be looking if we were trying to prove a black hole existed at the center of our Galaxy? What is the Schwarzschild radius, the event horizon, the singularity?
Normal Galaxies
Compare spirals, barred spirals, ellipticals, S0's (lenticulars), and Irregular (Irr) galaxies. Consider their gas and dust content, their bulges, their disks, their star formation histories, their origins, the relative ages of their stars, their colors. How are the formation processes for spirals and elliptical galaxies different?
What is the Hubble sequence? Sketch the Hubble sequence. "The Hubble sequence is a morphological sequence"; what does this mean? How does the appearance of disk like galaxies change as they move down the Hubble sequence? Contrast Sa galaxies to Sc galaxies.
Make a table or diagram which indicates the different length scales on which we see galaxies cluster. Roughly, what is the scale for an individual galaxy? What are the scales for the Great Wall and Voids? How do these compare to the size of the Universe? Consider the volume of the Universe occupied by these features. What volumes of the Universe do these features occupy? Does the observed inhomogeneity rule out the Cosmological Principle?
Active Galactic Nuclei (AGNs)
What features of AGNs differentiate them from normal galaxies? Are AGNs all fundamentally different? Are they thought to be oddballs or are they thought to fit into the scheme of galaxy evolution? What are the bases for the answers to the preceding questions? What difference would I see if I compared the spectra of AGNs to normal galaxies. What are the different types of AGNs? Roughly what are their properties? Explain the difference between stellar (thermal) and nonstellar (nonthermal) emission. What is the physical interpretation of electromagnetic radiation (as defined in class)? What is synchrotron emission?
How is Hubble's law used to infer distances to galaxies? What is the Doppler shift? What is the redshift, z? For slow speeds, how are z and the speed of the object related?
What are the principal observationalfacts which make AGNs difficult to understand? How can the time variability of an object be used to infer upper limits on its size? If the light from an object varies on a time scale of 1 hour, roughly, what is the largest size the object could have?
Black holes are the energy engines for AGNs. What are the properties of black holes which make them natural engines for AGNs? Consider their sizes and their energy generation efficiencies. Roughly how many stars per year must AGN eat to power themselves? What is meant by Accretion? What is a tidal force? Why are tidal forces important for black hole accretion? Using tidal forces as the basis for your argument, why do we think we understand why QSOs are usually seen at great distances from the Milky Way (-->they existed early in the lifetime of the Universe_? That is, why do AGNs seem to shut-off?
What is the evidence that our ideas for black hole as the energy engines for AGNs are correct? What Hubble Space Telescope (HST) observations support black holes as energy engines?