Radiative Processes in Astrophysics

by Rybicki, George B.; Lightman, Alan P.

• ISBN13: 9780471827597
• ISBN10: 0471827592
• Edition: 1st
• Format: Paperback
• Copyright: 1991-01-08
• Publisher: Wiley-VCH

Summary

Radiative Processes in Astrophysics: This clear, straightforward, and fundamental introduction is designed to present-from a physicist's point of view-radiation processes and their applications to astrophysical phenomena and space science. It covers such topics as radiative transfer theory, relativistic covariance and kinematics, bremsstrahlung radiation, synchrotron radiation, Compton scattering, some plasma effects, and radiative transitions in atoms. Discussion begins with first principles, physically motivating and deriving all results rather than merely presenting finished formulae. However, a reasonably good physics background (introductory quantum mechanics, intermediate electromagnetic theory, special relativity, and some statistical mechanics) is required. Much of this prerequisite material is provided by brief reviews, making the book a self-contained reference for workers in the field as well as the ideal text for senior or first-year graduate students of astronomy, astrophysics, and related physics courses. Radiative Processes in Astrophysics also contains about 75 problems, with solutions, illustrating applications of the material and methods for calculating results. This important and integral section emphasizes physical intuition by presenting important results that are used throughout the main text; it is here that most of the practical astrophysical applications become apparent.

Author Biography

George B. Rybicki received his B.S. degree in physics from Carnegie-Mellon University and his Ph.D. in physics from Harvard University. He is a physicist at the Harvard-Smithsonian Center for Astrophysics and lecturer in the Astronomy Department at Harvard. His research interests include stellar atmospheres, stellar dynamics and radiative transfer. Alan P. Lightman received his A.B. degree in physics from Princeton University and his Ph.D. in theoretical physics from the California Institute of Technology. He was a research fellow at Cornell and then an Assistant Professor of Astronomy at Harvard University from 1976–1979. He is presently at the Harvard-Smithsonian Center for Astrophysics. His research includes work in general relativity, the astrophysics of black holes, radiation mechanisms, and stellar dynamics. He is also a coauthor of Problem Book in Relativity and Gravitation (1975).

Table of Contents

Chapter 1

Fundamentals of Radiative Transfer

1.1 The Electromagnetic Spectrum; Elementary Properties of Radiation

1.2 Radiative Flux

Macroscopic Description of the Propagation of Radiation

Flux from an Isotropic Source-The Inverse Square Law

1.3 The Specific Intensity and Its Moments

Definition of Specific Intensity or Brightness

Net Flux and Momentum Flux

Radiative Energy Density

Radiation Pressure in an Enclosure Containing an Isotropic Radiation Field

Constancy of Specific Intensity Along Rays in Free Space

Proof of the Inverse Square Law for a Uniformly Bright Sphere

1.4 Radiative Transfer

Emission

Absorption

The Radiative Transfer Equation

Optical Depth and Source Function

Mean Free Path

Radiation Force

1.5 Thermal Radiation

Blackbody Radiation

Kirchhoff's Law for Thermal Emission

Thermodynamics of Blackbody Radiation

The Planck Spectrum

Properties of the Planck Law

Characteristic Temperatures Related to Planck Spectrum

1.6 The Einstein Coefficients

Definition of Coefficients

Relations between Einstein Coefficients

Absorption and Emission Coefficients in Terms of Einstein Coefficients

1.7 Scattering Effects; Random Walks

Pure Scattering

Combined Scattering and Absorption

1.8 Radiative Diffusion

The Rosseland Approximation

The Eddington Approximation; Two-Stream Approximation

Problems

References

Chapter 2

Basic Theory of Radiation Fields

2.1 Review of Maxwell's Equations

2.2 Plane Electromagnetic Waves

2.3 The Radiation Spectrum

2.4 Polarization and Stokes Parameters 62

Monochromatic Waves

Quasi-monochromatic Waves

2.5 Electromagnetic Potentials

2.6 Applicability of Transfer Theory and the Geometrical Optics Limit

Problems

References

Chapter 3

Radiation from Moving Charges

3.1 Retarded Potentials of Single Moving Charges: The Liénard-Wiechart Potentials

3.2 The Velocity and Radiation Fields

3.3 Radiation from Nonrelativistic Systems of Particles

Larmor's Formula

The Dipole Approximation

The General Multipole Expansion

3.4 Thomson Scattering (Electron Scattering)

3.5 Radiation Reaction

3.6 Radiation from Harmonically Bound Particles

Undriven Harmonically Bound Particles

Driven Harmonically Bound Particles

Problems

Reference

Chapter 4

Relativistic Covariance and Kinematics

4.1 Review of Lorentz Transformations

4.2 Four-Vectors

4.3 Tensor Analysis

4.4 Covariance of Electromagnetic Phenomena

4.5 A Physical Understanding of Field Transformations 129

4.6 Fields of a Uniformly Moving Charge

4.7 Relativistic Mechanics and the Lorentz Four-Force

4.8 Emission from Relativistic Particles

Total Emission

Angular Distribution of Emitted and Received Power

4.9 Invariant Phase Volumes and Specific Intensity

Problems

References

Chapter 5

Bremsstrahlung

5.1 Emission from Single-Speed Electrons

5.2 Thermal Bremsstrahlung Emission

5.3 Thermal Bremsstrahlung (Free-Free) Absorption

5.4 Relativistic Bremsstrahlung

Problems

References

Chapter 6

Synchrotron Radiation

6.1 Total Emitted Power

6.2 Spectrum of Synchrotron Radiation: A Qualitative Discussion

6.3 Spectral Index for Power-Law Electron Distribution

6.4 Spectrum and Polarization of Synchrotron Radiation: A Detailed Discussion

6.5 Polarization of Synchrotron Radiation

6.6 Transition from Cyclotron to Synchrotron Emission

6.7 Distinction between Received and Emitted Power

6.8 Synchrotron Self-Absorption

6.9 The Impossibility of a Synchrotron Maser in Vacuum

Problems

References

Chapter 7

Compton Scattering

7.1 Cross Section and Energy Transfer for the Fundamental Process

Scattering from Electrons at Rest

Scattering from Electrons in Motion: Energy Transfer

7.2 Inverse Compton Power for Single Scattering

7.3 Inverse Compton Spectra for Single Scattering

7.4 Energy Transfer for Repeated Scatterings in a Finite, Thermal Medium: The Compton Y Parameter

7.5 Inverse Compton Spectra and Power for Repeated Scatterings by Relativistic Electrons of Small Optical Depth

7.6 Repeated Scatterings by Nonrelativistic Electrons: The Kompaneets Equation

7.7 Spectral Regimes for Repeated Scattering by Nonrelativistic Electrons

Modified Blackbody Spectra; y>1

Unsaturated Comptonization with Soft Photon Input

Problems

References

Chapter 8

Plasma Effects

8.1 Dispersion in Cold, Isotropic Plasma

The Plasma Frequency

Group and Phase Velocity and the Index of Refraction

8.2 Propagation Along a Magnetic Field; Faraday Rotation

8.3 Plasma Effects in High-Energy Emission Processes

Cherenkov Radiation

Razin Effect

Problems

References

Chapter 9

Atomic Structure

9.1 A Review of the Schrödinger Equation

9.2 One Electron in a Central Field

Wave Functions

Spin

9.3 Many-Electron Systems

Statistics: The Pauli Principle

Hartree-Fock Approximation: Configurations

The Electrostatic Interaction; LS Coupling and Terms

9.4 Perturbations, Level Splittings, and Term Diagrams

Equivalent and Nonequivalent Electrons and Their Spectroscopic Terms

Parity

Spin-Orbit Coupling

Zeeman Effect

Role of the Nucleus; Hyperfine Structure

9.5 Thermal Distribution of Energy Levels and Ionization

Thermal Equilibrium: Boltzmann Population of Levels

The Saha Equation

Problems

References

Chapter 10

Radiative Transitions

10.1 Semi-Classical Theory of Radiative Transitions

The Electromagnetic Hamiltonian

The Transition Probability

10.2 The Dipole Approximation

10.3 Einstein Coefficients and Oscillator Strengths

10.4 Selection Rules

10.5 Transition Rates

Bound-Bound Transitions for Hydrogen

Bound-Free Transitions (Continuous Absorption) for Hydrogen

Radiative Recombination--Milne Relations

The Role of Coupling Schemes in the Determination of f Values

10.6 Line Broadening Mechanisms

Doppler Broadening

Natural Broadening

Collisional Broadening

Combined Doppler and Lorentz Profiles

Problems

References

Chapter 11

Molecular Structure

11.1 The Born-Oppenheimer Approximation: An Order of Magnitude Estimate of Energy Levels

11.2 Electronic Binding of Nuclei

The H2+ Ion

The H2 Molecule

11.3 Pure Rotation Spectra

Energy Levels

Selection Rules and Emission Frequencies

11.4 Rotation-Vibration Spectra

Energy Levels and the Morse Potential

Selection Rules and Emission Frequencies

11.5 Electronic-Rotational-Vibrational Spectra

Energy Levels

Selection Rules and Emission Frequencies

Problems

References

Solutions

Index