Material: Topic 1 (drawn from parts of Chapters 23-27), Topic 2 (Chapter 23 and part of 24)), and whatever I get in Topic 3 review. I will finish the review after the conclusion of class on Tuesday.

Details:

INTRODUCTION

• Cosmology: Define cosmoloty? How has cosmology (as a science) evolved from the time of the Greeks to current times?
• What makes a model scientific? Contrast science and philosophy. Compare Universe to universe.
• Basic Observations of cosmology:
  • The expanding Universe, Hubble's Law (24.3), V.M. Slipher and E. Hubble, Doppler shift vs cosmological redshift (24.3), naive interpretation of Hubble's Law. How did the Principle of Mediocrity contribute to our interpretation of Hubble's Law?
  • Cosmic Microwave Background Radiation (CMBR), What is it? When did it arise? What do we see when we observe the CMBR? What are the properties of the CMBR? (26.7) What is horizon problem? (27.4)
  • Chemical composition of the normal matter in the Universe is roughly 90 % hydrogen and ~ 10 % helium; everyting else heavier than helium is referred to as a metal and comprise only a small part of the Universe. (As a note, what is the make-up of the overall Universe? What is dark matter? What is dark energy? What fraction of the Universe is normal matter?)
• Cosmological Principles:
  • Copernican Principle (Principle of Mediocrity), annual trigonometric parallax (pp 27-28), explain how Hubble's Law may be explained through uniform expansion of the Universe, Are we at the Center of the Galaxy? Describe the works of Herschel and Kapteyn, and Shapley (23.2) What did Herschel, Kapteyn, and Shapley conclude about the location of the Sun in the Milky Way galaxy? Who was correct? Why did the ones who were in error reach their erroneous conclussions (talk about dust, what is dust?)? What is the location of the Sun and the true shape of the Milky Way galaxy?
  • Cosmological Principle (26.1), what is it? What is meant by homogeneity and isotropy since the Universe is clearly not bland and uniform on all scales? In the Cosmological Principle can the Universe evolve in time? Give a nice example that shows that the Universe is nearly homogeneous and isotropic on all large scales.
  • Perfect Cosmological Principle, what is it? Is it currently considered by astronomers when they model the Universe? It is not, what are some reasons why the Perfect Cosmological Principle is not in favor? What is the Cosmological Constant? It was proposed by Einstein, why? Why did Einstein withdraw his suggestion? Has this idea returned to favor today?
  • Anthropic Principle, What is the Anthropic Principle? Does Jim like the Anthropic Principle? Why does Jim like (or dislike) the Anthropic Principle?
• What is the Big Bang Theory? What does the Big Bang Theory say? Upon what observations is the Big Bang Theory based? Is the Big Bang on a firm observational footing?
• Compare and contrast light year and parsec. What are they?

• Normal Galaxies (ellipticals, spirals, barred spirals, S0s, and Irregulars, Hubble Galaxy Classification scheme (24.1)
• Milky Way Galaxy:
  • What is the Hubble classification of the Milky Way galaxy
  • Briefly describe the apparance of the Milky Way galaxy. What are the three primary regions in the Milky Way galaxy? What are the properties of the disk, the halo, and the bulge of the Milky Way? What are the properties of the Milky Way galaxy, in general?
  • A black hole lives in the center of the Milky Way galaxy. What is a black hole? What are the properties of the black hole in the center of the Milky Way galaxy? What is the Event Horizon, the singularity, and the Schwarzschild radius? What is Cosmic Censorship? Space and time are consiered coordinates, but are treated differently, how so? How doe their natures change at event horizons? What is the escape speed from a black hole? What are S2 and S6? What is Sgr? Where is Sgr A? What are tidal forces? How often must the black hole in the center of our Galaxy eat a star to power the nucleus of our Galaxy?
  • What are Population I stars? What are Population II stars? Where are each found?
  • What are some of the differences between nonrotating and rotating black holes? What is the ergosphere? What is the static limit? What is the Penrose Process?
  • How is the structure of the Milky Way galaxy determined? What objects are used to study the structure of the Milky Way galaxy? Why are OB stars, H I regions, H II regions, Giant Molecular Clouds used to study the spiral arms of our Galaxy? What is meant by H I? by H II? What are Cepheid variables? What is the Period-Luminosity Relation? Why are variable stars like Cepheids and RR Lyrae stars valuable to astromers? What are rotation curves? How are rotation curves found in the region outside of the visible disk of our Galaxy, that is, outside of where we find stars and star forming regions (OB star, H II regions, Giant Molecular Clouds). How far do rotation curves extend beyond the visible disk of our Galaxy?
  • Describe how rotation curves are used to determine the masses of spiral galaxies. (Note--how fast does the Sun move in its orbit about the center of the Milky Way galaxy? How large is the orbit of the Sun about the center of the Milky Way galaxy?) What is the significance of the fact that most rotation curves are nearly flat (the galaxy spins at nearly the same speed at large distances as at small distances from its center)? How do the mass estimates from rotation curve affect the question of the amount of Dark Matter in our Galaxy?
  • What are MACHOs? Where are MACHOs found? How are MACHOs detected? (What is gravitational lensing?) What fraction of the Dark Matter might be contained in MACHOs?

  Hubble's Galaxy Classification Scheme and the Hubble Tuning Fork Diagram
  • Sketch Hubble's Tuning Fork Diagram. Pay care to to show the flattening of ellipticals changes, how bulge size, winding of spiral arms changes from class to class. How do the properties of the galaxies in terms of gas and dust content, stellar populations vary from class to class?
  • Describe Elliptical, Spiral, Barred Spiral, SBO, S0, and Irregular galaxies. What are Lenticulars? What the differences between Sa, Sb, and Sc galaxies, E0 to E7 galaxies, Irr I and Irr II galaxies.
  • Is the Hubble Tuning Fork diagram an evolutionary sequence? Do galaxies evolve?
  • What kinds of galactic collisions occur? What are the results of collisions between similar mass disk galaxies, galaxies of greatly differing masses? Are collisions thought to be exceedingly rare? How many of a role do galactic colliions play in galaxy evolution? What are Supergiant Ellipticals? Where do they arise? Describe the interactions suffered (and to be suffered) by the Milky Way Galaxy. Describe the evolution and apperance of the Antennae, Cartwheel, and Mice galaxies.
  • What is the extragalacitc distance ladder? What is the Tully-Fisher method (how does it work)? How do Cepheids fit into the scheme? What are other ways to determine distances of distant objects?
  • What is the cosmological redshift?
  • Describe how objects cluster in the Universe. Describe the properties of clusters of galaxies (such as Virgo and Coma). Why are there no spirals found near the centers of rich clusters of galaxies? What are cD galaxies? Why are supergiant Elliptical galaxies often times found near the centers of rich clusters of galaxies? How were observations of galaxy clusters used to detect Dark Matter? Who was the first astronomer to suggest the existence of Dark Matter? (What is meant by Dark Matter?)
  • What is meant by look-back time?`
  • What are voids, filaments, and the Sloan Great Wall? How were these features detected? Does the observed structure in the Universe rule out the Cosmological Principle as a viable asuumption concerning the nature of the Universe? Why or why not. Is the structure observed in the Universe consistent with the CMBR observations?

  Active Galactic Nuclei (AGNs)

  • What is the major difference between the way normal galaxies and active galactic nuclei produce their emission (How do their spectra differ)? What is meant by thermal emission? nonthermal emission?
  • Describe the different families of bright AGNs. Which class is the most luminous? Which classes are found in normal galaxies (or are all AGNs found in normal galaxies)? What fraction of bright galaxies are AGNs?
  • What observed features of AGNs make them difficult to understand? Are AGNs such bizarre objects that are considered to be completely outside the realm of normal galaxies or are they considered to extreme examples of normal galactic evolution? Upon what evidence is the answer to the preceding question based?
  • How is rapid variability used to determine the maximum size of a emitting region?
  • How was the Hubble Law used to find distances to QSOs? What does QSO mean?
  • What are the models used to explain the nonthermal spectra of AGNs, the efficient energy production of AGNs, and the small size of AGNs? What evidence supports our picture of the energy engines of AGNs?
  • What are supermassive Black Holes? Describe the evidence that the Universe contains supermassive Black Holes. Describe the supermassive Black Hole in the nucleus of our Galaxy. How are supermassive Black Holes thought to be produced? How efficient are black holes as energy engines? What fuels the black holes found in AGNs? What is the radius of 1 billion Solar mass black hole? Desribe the relationship between supermassive black holes and the masses of the bulges of the galaxies in which they are found. What is the significance of this relationship?