Properties of Galaxies
Spring 2002
    Unique No. 45655 TTH 12:30-2:00 RLM 15.216B


3.1 Surface Photometry

  • Review of techniques (photographic,CDD)
  • Radial brightness profiles:
    • Systematics
    • Analytic fitting functions
  • D galaxies: properties of cD halos
  • Cores: ground-based and HST observations

3.2 Families of Ellipsoidal Stellar Systems

  • Global and core parameter correlations
  • Three kinds of stellar systems: bulges + ellipticals, Sphs, globulars
  • Relationship between Sph and S + I galaxies: Introduction

3.3 The Fundamental Plane of Elliptical Galaxies

  • Global and core parameter correlations
  • Scalar virial theorem; derivation of the fundamental plane equations
  • Implications for galaxy formation; M/L (L )

3.4 Stellar Dynamics:Observations

  • Measurement techniques:
    • cross-correlation,Fourier quotient,Fourier correlation quotient,...
  • Line-of-sight velocity distributions (LOSVDs)
  • Observations of rotation and velocity dispersion pro •les
  • Velocity anisotropy: the diagram
  • Observational confirmation of triaxiality and anisotropy:
    • Minor-axis rotation
    • Shapes of E galaxies:statistics of apparent shapes
    • Isophote twists
    • Dust rings:implications for E shapes

3.5 Isophote Shapes:Boxy and Disky Es

  • Measurements of isophote shapes: a (4)/a
  • Correlations of a (4)/a with physical properties
  • Physical dichotomy of E galaxies into
    • (1)High-L , nonrotating, boxy, anisotropic Es with cuspy cores, and
    • (2)Medium-and low-L , rotating, disky, approximately isotropic and coreless Es
  • Proposed revision of the Hubble sequence: boxy E –disky E –S0 –Sa –Sb –Sc –...–Im
  • Exceptions: Boxy bulges and low-L boxy Es: origin

3.6 Collisionless Dynamics: Theory

  • Stellar systems are fundamentally more complicated than gases:
    • Long mean free path
  • Characteristic times: crossing time; relaxation time
  • Distribution function
  • Fundamental equations of macroscopic stellar dynamics:
    • Collisionless Boltzmann equation
    • Poisson equation
  • First moment equations =basic equations of stellar hydrodynamics:
    • The Jeans equations
  • Second moment equations: tensor virial theorem
  • Application to diagram ==> anisotropy

3.7 Galaxy Models. I. f =f (E, Lz )

  • Jeans Theorem
  • Models with f =f (E ):polytropes,isothermals,King models
    • Emphasize:similarities between stellar dynamical and gas case (i.e.,stars)

    • Core mass-to-light ratios
  • Models with f =f (E,Lz )

3.8 Globular Cluster Observations and Models

  • Density distributions
  • Velocity dispersion profiles
  • Models with a range of stellar masses m

3.9 Stellar Orbits in Ellipsoidal Stellar Systems

  • Orbits in a spherical potential
  • Orbits in axisymmetric potentials: classical integrals
  • Orbits in triaxial potentials

3.10 Galaxy Models.II.Galaxy = weighti orbiti

  • Schwarzschild ’s method; examples
  • Spherical maximum entropy models; examples
  • Axisymmetric maximum entropy models; examples

3.11 Dynamical Evolution of Ellipticals and Globular Clusters: Theory

  • Phase mixing and violent relaxation
    • Origin of the density distribution
  • Two-body encounters and relaxation
    • Heat capacity of a self-gravitating stellar system is negative
    • Core collapse: single- simulations
    • Stopping core collapse via binaries
    • Gravothermal oscillations
    • Complications: range of , primordial binaries, stellar evolution, physical stellar collisions, stellar coalescence, runaway stellar mergers,...
  • External influences:
    • Tidal effects
    • Disruption of globular clusters by galactic disk shocking
    • Relation between present and primordial globular cluster population

3.12 Dynamical Evolution of Ellipticals and Globular Clusters: Observations

  • Post-core-collapse density distributions in globulars
  • Mass segregation
  • Stellar population gradients:blue stragglers
  • Stellar population gradients in bulges and Es <== effects of high stellar density

3.13 Supermassive Black Holes (BHs)in Galactic Nuclei

  • Brief motivation: nucelar activity (see §9)
  • Origin of seed BHs via evolution of dense stellar systems
  • Stellar-dynamical search for BHs
  • Gas-dynamical search for BHs
  • BH demographics
  • Flashes when stars are accreted by BHs

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31 November 2001
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