Radiative Processes

Course Description

This course covers astrophysical radiation processes, focusing on the physical mechanisms that produce, modify, and diagnose radiation from astrophysical plasmas, and develops a quantitative framework for continuum and line emission in environments such as interstellar gas, nebulae, accretion flows, and hot ionized media. The course begins with essential background in special relativity, statistical mechanics, and thermodynamic equilibrium, followed by the radiative transfer equation and its physical interpretation (emission, absorption, and scattering), and then examines major continuum processes including blackbody radiation, thermal bremsstrahlung, synchrotron and cyclotron emission, and Compton scattering. The second half focuses on atomic processes governing line emission and absorption, including atomic structure, selection rules, Einstein coefficients, collisional and radiative processes, and ionization balance, with applications to interpreting spectra from photoionized and collisionally ionized plasmas, absorption lines, optical depth effects, and the curve of growth. Emphasis is placed on analytic calculations and order-of-magnitude estimates connecting physical conditions to observable radiation, including the computation of emissivities, absorption coefficients, cooling rates, and characteristic timescales, and the inference of source properties from observed spectra.

Code

ASTRO 441

Credits

3

Subject

ASTRO