**Astronomy & Astrophysics Topics**

**Physics and Astronomy Department Candidacy Exam**

**Introduction:** The following list of topical areas and subtopics covers the areas of astronomy and
astrophysics which students are expected to have some mastery of. This is a very broad research area
and examinees are not expected to be deeply knowledgeable in all topics. Typically they should be
somewhat knowledgeable of topics well removed from their research area(s), and fairly knowledgeable
about all topics of close relevance to their research area. The examining committee and student may,
after consultation, refine and focus this list.

**Basic Observational Astronomy:** Celestial sphere, coordinates, photometric systems, magnitude
equation, distance modulus, extinction, parallax, spectral types, telescopes, resolution, basic
spectrometer properties, HR diagram

**Radiation Processes:** radiative transfer terms definition and usage, the fundamental equation of
radiative transfer, definition of source function and optical depth, electromagnetic spectrum regions,
blackbody radiation, Einstein A and B coefficients, Maxwell equations and electromagnetic waves,
power emitted from accelerated charges (amount, angular pattern, and polarization), Four vectors,
covariance, relativistic transformations involving E and B fields, free-free emission (bremstrahlung),
bound-free (photo-electric effect) and free-bound processes and spectra, cyclotron and synchrotron
radiation, Compton scattering (cross section and effect on spectrum), inverse compton scattering, pair
creation and annihilation, plasma effects of rotation measure and dispersion measure, basic atomic
structure of single-electron and multi-electron atoms spectroscopic notation, definitions of permitted and
forbidden emission lines, line broadening (natural, thermal, and collisional), energy levels of diatomic
molecules, symmetries, rotation-vibration spectra of molecules.

**Stellar Atmopheres:***Energy Transport:* Conductive, radiative and convective energy transport and conditions for each, basic
thermodynamics
*Stellar Continua:* Sources of continuous opacity, Saha equation, shapes of stellar continua, changes with
temperature, gravity, metallicity, limb darkening, line blanketing
*Model Photospheres:* Hydrostatic equilibrium, radiative equilibrium, plane parallel assumption, LTE, a
schematic understanding the structure is calculated and what is needed to specify the structure
*Spectral Lines:* Boltzmann equation, Gaussian and Lorentz profiles, Voigt function, line broadening
mechanisms and what they diagnose about a stellar atmosphere, equivalent width, Zeeman effect,
contribution function, curve of growth, behavior of spectral lines with temperature, gravity, and
metallicity, line blanketing
*Advanced Topics:* Determining fundamental stellar properties (temperature, radii, abundance, rotation),
basics about NLTE (when it is important, first order effects), stellar winds and the formation of a PCygni
profile

**Stellar Structure:***Equations of Stellar Structure:* Basic hydrodynamics, hydrostatic equilibrium, mass continuity, energy
generation, radiative transport, convective transport, required constitutive relations
*Homologous Models & Polytropes:* Homologous relations, definition and examples of polytropes
*Nuclear Energy Generation:* P-P chain and its properties, triple-alpha reaction, CNO cycle and its
properties, minimum mass for hydrogen fusion and brown dwarfs, He fusion and beyond, iron
catastrophe
*Pre-Main Sequence Stellar Evolution:* Hertzsprung-Russell diagram, Jeans mass and Radius, Pre-main
sequence evolutionary tracks, accretion disk diagnostics, feedback into the interstellar medium
*Post-Main Sequence Stellar Evolution:* Evolution of low mass stars including formation of planetary
nebulae and white dwarfs, evolution of high mass stars to supernova and neutron star or black hole
formation

**Compact Objects:***Special Relativity:* Relativistic kinematics, Lorentz transformations, Lorentz invariants and covariance
*General Relativity:* curvature, geodesics, classic experimental tests, black holes, Schwarzschild radius,
redshift, gravitational waves
*Post-Main Sequence Stars:* quantum degeneracy pressure in white dwarfs and neutron stars, mass-radius
relationship, Chandrasekhar and neutron star mass limits
*Accreting Systems:* Eddington luminosity and mass accretion limit, Bondi accretion, Shakura-Sunyaev
alpha disks

**Nebular Astrophysics and the Interstellar Medium***Physical Processes:* Collisions, charge Exchange, photoexcitation, decay, fluorescence, photoionization,
recombination, collisional ionization, energy levels, collisional excitation and deexcitation
*Forbidden Lines:* critical density and excitation, optical depth, examples

*HII Regions:* Stromgren sphere, inclusion of dust, overall spectrum, temperature, abundances, simple
applications

*Planetary Nebulae:* Formation, excitation, spectrum

*Dynamics:* Kepler’s Laws, virial theorem, fluid equations, instabilities, shocks and ionization fronts,
gravitational collapse, simple applications

*ISM:* Phase of the ISM, dispersion and rotation measures

*Supernova remnants:* dynamics, Sedov phase, line spectroscopy, cosmic ray production

**Normal and Active Galaxies:**

*Galaxy phenomenology:* Discovery of galaxies, Shapley-Curtis debate, Hubble’s classification scheme

*Spiral galaxies:* structure of the Milky Way, the Galactic center region, velocity dispersions, rotation
curves, dark matter inferences, Tully-Fisher relation, spiral structure, density wave theory

*Elliptical Galaxies:* triaxiality, subclasses of ellipticals, Faber-Jackson relation, King’s model,
gravitational relaxation, gas cooling

*Active Galaxies:* Seyfert galaxies, broad and narrow emission line regions, reverberation mapping,
Lyman-alpha forest, radio galaxies, lobes and hot spots, VLBI, unification schemes

*Extragalactic Jet systems and Microquasars:* quasar and blazar phenomology, superluminal motion,
Doppler boosting, shock acceleration

**Structure of the Universe and Cosmology:**

*Cosmic structures:* distance determination techniques, Hubble’s Law, galaxy distributions, galaxy
clusters, supernova surveys, large scale structure, gravitational lensing

*Newtonian cosmology:* Olber’s paradox, the cosmological principle, cosmochronology – dating the
universe, Friedmann’s equation and solutions, critical density, matter-dominated universes

*Relativistic cosmology:* Robertson-Walker metric, radiation and cosmological constant in Friedmann’s
equation, global solution for our universe, particle horizons

*Observational cosmology:* deceleration parameter, angular diameter and luminosity distances,
cosmological determinations using supernovae

*Early universe:* cosmic microwave background anticipation and discovery, COBE and WMAP results
and implications, acoustic oscillations and gravitational seed perturbations, recombination, redshift of
last scattering, primordial nucleosynthesis, inflation, GUT era.