Astronomy 601 - Fall 2006“Radiative Processes”InstructorProf. Massimo RicottiOffice: CSS 0213E-mail: [email protected]: (301) 405 5097Office hours: by appointmentClass web page: http://www.astro.umd.edu/∼ricotti/NEWWEB/teaching/ASTR601.htmlScheduleLectures on Tuesday and Thursday from 2:00pm to 3:15pmRoom CSS 0201Course DescriptionThe emission, absorption and scattering of radiation by matter with astrophysical appli-cations. Emphasis on basic theory and problem-solving. (i) Radiative transfer: specificintensity, transfer equation, opacity, diffusion, scattering. (ii) Statistical mechanic s of mat-ter and radiation: LTE, level populations, rate equations. (iii) Electrodynamics: Maxwellequations, spectra of radiation, polarization, dipole and multipole radiation, Thompsonscattering. (iv) Plasma radiation: bremsstrahlung and synchrotron emission, Comptonscattering, EM wave propagation in plasmas. (v) Atomic and molecular radiation: energylevels, Einstein coefficients, oscillator strengths, line broadening.TextbooksRequired: The Physics of Astrophysics Vol ume I: Radiation by F.H. ShuRecommended: Radiative Processes in Astrophysics by G. Rybicki and A. LightmanCourse GradingHomeworks 50%Midterm Exam 20%Final Exam 30%There will be one in-class Midterm exam and an in-class Final (the dates of the exams areshown below in the “Tentative course outline” section). Class participation is stronglyencouraged. Class attendance is instead required. Homework will be assigned every weekor every other week. Their due dates will be announced at the time they are assigned.On the due date the students will be expected to turn in their homework in class. Thehomework turned in will be graded and returned to the students. I will provide solutionsand discuss them in class.1Letter Grades85%-100% A70%-85% B55%-70% C40%-55% DI may rescale the gra des depending on the average class performance. Of course therescaling can o nly increase your final grade.Tentative Course Outline - 28 lectures & 2 examsA. Radiative transfer - 6 lectures1. Th Aug. 31: Radiation definitions; specific intensity, photon distribution function,occupation number, energy density, flux, momentum flux, radiation pressure (ShuCh. 1; R-L § 1.1-1.3)2. Tu Sept. 5: Equation of radiative transfer; emissivity and opacity, blackbodyradiation, radiation thermodynamics, Stefan-Boltzmann law (Shu Ch. 1; R-L § 1.4-1.5)3. Th Sept. 7: Bose Einstein statistics; Planck spectrum; Rayleight-Jeans and Wienlimits, radiation constant, effective temperature, color temperature a nd brightnesstemperature (Shu Ch. 1,2; R-L § 1.5)4. Tu Sept. 12: Moment equations; radiative diffusion approximation, Rosselandmean opacity, scattering and random walks (Shu Ch. 2; R-L § 1.7-1.8)5. Th Sept. 14 : General solution of radiative transfer equation, source function,optically-thick and -thin limits, LTE, line for matio n, absorption and emission spec-tra, limb darkening (Shu Ch. 3; R-L § 1.4)6. Tu Sept. 19: Plane-parallel atmospheres: radiative equilibrium, grey opacity,Eddington approximation (Shu Ch. 4; R-L § 1.8)B. Statistical Mechanics of matter and radiation - 5 lectures1. Th Sept. 21: Statistical mechanics, definitions of entropy, temperature, chemicalpotential, pressure, grand canonical pa rt itio n function (Gibbs sum), Thermodynam-ics: thermodynamic identity, grand potential, entropy (Shu Ch. 6; R-L § 1.5)2. Tu Sept. 26: Quantum statistical mechanics: Fermion and Boson partition func-tions, grand potentials, occupation numbers (Shu Ch. 6; R-L § 1.5)3. Th Sept. 28: Statistical equilibria: reaction equilibrium, Boltzmann law for inter-nal level populations, Saha equation f or ionization state po pulations, free particlepartition functions, application to partial ionization a nd absorption line strengths(Shu Ch. 7; R-L § 9.5)4. Tu Oct. 3: Rate equations and detailed balance, Einstein A and B coefficients,relations to emissivity, absorption opacity, cross-section, oscillator strength (ShuCh. 8; R-L § 1.6)25. Th Oct. 5: Collisional processes: rate coefficients, Einstein relations, radiationtransfer in moving media, Sobolev (LVG) approximation, thick and thin limits,photon trapping and escape probability (Shu Ch. 9)C. Classical Electrodynamics - 7 lectures1. Tu Oct. 10: Maxwell equations, vacuum electromagnetic wave equations, planeparallel waves, EM energy and momentum flux [Poynting vector and Maxwell stresstensor] (Shu Ch. 11; R-L § 2 .1-2.2)2. Th Oct. 12: Fourier spectra of radiation, elliptically polarized waves (Shu Ch. 12;R-L § 2.3-2.4)3. Tu Oct. 17: Midterm exam4. Th Oct. 19: Stokes parameters and polarization, application to dust polarization(Shu Ch. 12; R-L § 2.4)5. Tu Oct. 24: EM wave equation with sources, scalar and vector potentials, gaug etransformations, retarded p otentials (Shu Ch. 13; R-L § 2.5)6. Th Oct. 26: G r een’s function solutions for inhomogeneous wave equations, singleparticle (Lienard-Wiechert) retarded potential (Shu Ch. 13; R-L § 3.1-3.2)7. Tu Oct. 31: Wave zone, electric dipole ra diatio n, radiation reaction, Thomsonscattering Rayleigh scattering (Shu Ch. 14; R-L § 3.3-3.6)8. Th Nov. 2: Multipole radiation: magnetic dipole, electric quadrupole, permittedand forbidden transitions ( Shu Ch. 1 5; R-L Ch. 5 )D. Plasma radiation and transfer - 5 lectures1. Tu Nov. 7: Thermal Bremsstrahlung (Shu Ch. 15; R-L Ch. 5)2. Th Nov. 9: Compton scattering (R-L Ch. 7)3. Tu Nov. 14: Radiation from relativistic charges (Shu Ch. 16, 17; R-L Ch. 4)4. Th Nov. 16: Synchrotron radiation (Shu Ch. 18, 1 9; R-L Ch. 6 )5. Tu Nov. 21: EM waves in plasmas, dispersion, Faraday rotation (Shu Ch. 20; R-LCh. 8)6. Th Nov. 23: Thanksgiving holidayE. Atomic and molecular structure and radiation (QED) - 5 lectures1. Tu Nov. 28: Electromagnetic Hamiltonian (Shu Ch. 21; R- L § 10.1)2. Th Nov. 30: Semiclassical theory of radiative transitions: quantum matter/radiationinteraction Hamiltonian, theory vector potential, E and B fields, semiclassical ra-diation energy density, absorption and emission Hamiltonians (Shu Ch. 22; R-L§ 10.1)3. Tu Dec. 5: Time dependent perturbation theory, propagator, one and two pho-tons transitions, tra nsition probabilities and rates for absorption/emission [Fermi’sgolden rule] (Shu Ch. 22; R-L § 10.1)34. Th Dec. 7: Dipole approximation, bound-bound transition rates and cross-sections, oscillator strengths, matrix elements, Einstein A and B coefficients forbound-bound transitions (Shu Ch. 23; R-L § 10.2,