ASTR202: Extragalactic Astronomy & Cosmology

Course content:

  • Structure of the Milky Way: the disk, bulge, stellar halo, and dark matter halo; spiral arms; review of stellar populations.
  • The distance ladder: review of parallax; standard candles; Cepheid variable stars; Type Ia supernovae; the Hubble law.
  • Properties of galaxies: morphological classification and the Hubble tuning fork; spectra and nebular emission lines; colours; luminosity function; surface brightness profiles; Tully-Fisher relation; Faber-Jackson relation; the fundamental plane.
  • Galaxy environments: the field; groups; clusters; the morphology-density relation; transformation of galaxies in dense environments.
  • Active galaxies: broad and narrow line active galactic nuclei (AGN); Seyfert galaxies; radio galaxies; quasars; blazars; accretion power and supermassive black holes; Eddington luminosity; unified model of AGN.
  • Dark matter: evidence from rotation curves of galaxies, velocity dispersion in galaxy clusters, dark matter haloes and structure formation, direct detection experiments, alternative theories.
  • The expanding Universe: cosmological redshift; the cosmological principle (homogeneity and isotropy); the Friedmann equation (Newtonian derivation); the fluid equation; the acceleration equation.
  • Simple cosmological models: evolution of matter or radiation dominated universes; curvature and the geometry of the Universe; Hubble parameter; density parameters; deceleration parameter; dark energy.
  • Cosmological observations: measuring density parameters; nucleosynthesis and the origin of light elements; the cosmic microwave background.
  • Problems with the Big Bang model: the flatness problem; the horizon problem; inflation.
  • Galaxy evolution: star formation history of the Universe; evolution in AGN fraction; evolution in the morphology-density relation; cosmological simulations of galaxy formation.

After completing this module students are expected to be able to:

  • Describe and explain the structure of galaxies, their basic properties (morphologies and colours), and how these vary with environment.
  • Perform simple calculations and measurements of galaxy and AGN properties (e.g., magnitudes and colours, surface brightness and effective radius, redshift, black hole mass, etc.).
  • Analyse statistical data on galaxy populations (e.g., luminosity functions, morphological fractions).
  • Critically discuss the evidence for the existence of dark matter and explain its role in the evolution of the Universe.
  • Apply the Friedmann, fluid, and acceleration equations in order to determine the properties of simple cosmological models (e.g., closed or open universes; de Sitter models).
  • Discuss the evidence for the Big Bang model, and explain how model parameters are measured observationally.
  • Explain the origin of the cosmic microwave background and the light elements (nucleosynthesis).
  • Explain problems with the Big Bang model and how these are solved by the inflation scenario.
  • Describe the modern approach to understanding the formation and evolution of galaxies within the standard cosmological framework and the relation between simulations and observations.