Atomic Astrophysics and Spectroscopy

Spectroscopy enables the precise study of astronomical objects and phenomena. Bridging the gap between physics and astronomy, this is the first integrated graduate-level textbook on atomic astrophysics. It covers the basics of atomic physics and astrophysics, including state-of-the-art research applications, methods and tools. The content is evenly balanced between the physical foundations of spectroscopy and their applications to astronomical objects and cosmology. An undergraduate knowledge of physics is assumed, and relevant basic material is summarized at the beginning of each chapter. The material is completely self-contained and features sufficient background information for self-study. Advanced users will find it handy for spectroscopic studies. A website hosted by the authors contains updates, corrections, exercises and solutions, as well as news items from physics and astronomy related to spectroscopy. A link to this can be found at www.cambridge.org/9780521825368. Cover......Page 1 Half-title......Page 3 Title......Page 5 Copyright......Page 6 Contents......Page 7 Preface......Page 11 Acknowledgements......Page 13 1.1 Atomic astrophysics and spectroscopy......Page 15 1.2 Chemical and physical properties of elements......Page 16 1.3 Electromagnetic spectrum and observatories......Page 18 1.4 Astrophysical and laboratory plasmas......Page 19 1.5 Particle distributions......Page 20 1.5.2.1 Black-body radiation and the Sun......Page 21 1.5.2.2 Maxwellian particle distribution......Page 23 1.6.2 Fermi–Dirac statistics......Page 24 1.7.1 Photometry and imaging......Page 25 1.8 Spectroscopic notation......Page 26 1.9 Units and dimensions......Page 27 2 Atomic structure......Page 29 2.1.1 Angular equation......Page 30 2.1.3 Rydberg states and hydrogenic energy levels......Page 31 2.1.4 Hydrogenic wavefunctions......Page 32 2.2 Quantum numbers and parity......Page 33 2.3 Spectral lines and the Rydberg formula......Page 34 2.4 Spectroscopic designation......Page 35 2.5.1 Non-equivalent electron states......Page 37 2.5.2 Equivalent electron states......Page 38 2.7 Intermediate coupling and jj coupling......Page 39 2.8 Hund's rules......Page 40 2.9 Rydberg formula with quantum defect......Page 41 2.10 Multi-electron atomic systems......Page 43 2.11 The Hartree–Fock method......Page 44 2.11.1 Configuration mixing......Page 47 2.12 Central-field approximation......Page 49 2.12.1 Thomas–Fermi–Dirac approximation......Page 50 2.13.1 Spin–orbit interaction......Page 51 2.13.2 The Dirac equation......Page 52 2.13.4 Dirac equation in a central field......Page 54 2.13.5 Multi-electron systems and the Breit equation......Page 56 2.13.6 Dirac–Fock approximation......Page 57 2.13.7 Z-scaling of fine structure......Page 58 3 Atomic processes......Page 60 3.1 Bound, continuum and resonance states......Page 61 3.2.1 Detailed balance......Page 63 3.2.3 Electron impact excitation......Page 64 3.2.6 Electron impact ionization......Page 65 3.2.7 Charge exchange recombination and ionization......Page 66 3.3 Theoretical approximations......Page 67 3.3.1 Channels in atomic processes......Page 68 3.3.2 Scattering phase shift......Page 69 3.4 The close coupling approximation......Page 70 3.4.1 Scattering matrices and cross section......Page 71 3.5.1 Single-channel problem......Page 73 3.5.2 Multi-channel problem......Page 74 3.5.3 Inner region......Page 75 3.5.4 Outer region......Page 76 3.5.6 Bound states: all channels closed......Page 77 3.5.7 The R-matrix codes......Page 78 3.6 Approximate methods......Page 79 3.6.1 Distorted wave method......Page 80 3.6.2 Coulomb–Born approximation......Page 82 3.6.5 Quantum defect theory......Page 83 4 Radiative transitions......Page 86 4.1 Einstein A and B coefficients......Page 87 4.2 Electron motion in an electromagnetic field......Page 89 4.2.1 Radiative transition probability......Page 90 4.3 Transition matrix elements......Page 91 4.5 Electric dipole approximation......Page 92 4.5.2 Oscillator strengths......Page 94 4.6 Central-field approximation......Page 95 4.7 Length, velocity and acceleration......Page 98 4.8 Oscillator strengths for hydrogen......Page 99 4.9 Configuration interaction......Page 100 4.10 Fine structure......Page 101 4.11 R-matrix transition probabilities......Page 102 4.12 Higher-order multipole transitions......Page 105 4.14 Dipole and non-dipole transitions in He-like ions......Page 107 4.15.1 Fine structure components of LS multiplets......Page 108 5 Electron–ion collisions......Page 111 5.1.1 Cross section......Page 112 5.1.2 Collision strength......Page 113 5.2 Theoretical approximations......Page 115 5.2.2 Multi-channel scattering matrix......Page 116 5.2.3 Multi-channel quantum defect theory......Page 117 5.3 Excitation rate coefficients......Page 118 5.4.1.1 Target eigenfunctions for Fe XVII......Page 119 5.4.2 Channel coupling......Page 122 5.4.4 Exchange......Page 123 5.4.6 Relativistic effects......Page 124 5.5 Scaling of collision strengths......Page 125 5.6 Comparison with experiments......Page 126 5.8 Electron impact ionization......Page 129 5.8.2 Semi-empirical formulae......Page 130 5.9 Auger effect......Page 131 5.9.1 Z-dependence of X-ray transitions......Page 133 6 Photoionization......Page 134 6.1 Hydrogen and helium......Page 135 6.3 Bound–free transition matrix element......Page 136 6.4 Central potential......Page 138 6.4.1 Energy dependence......Page 139 6.5 Generalized bound–free transition probability......Page 140 6.5.1 R-matrix photoionization calculations......Page 141 6.6 Channel coupling and resonances......Page 142 6.6.1 Partial cross sections......Page 143 6.6.2 Types of resonance......Page 144 6.6.2.2 Resonances below threshold in LS coupling......Page 145 6.6.2.3 Resonances below threshold due to fine structure......Page 146 6.6.2.4 Highly-excited core (HEC) resonances......Page 147 6.6.2.5 Photo-excitation of core (PEC) resonances......Page 148 6.6.2.6 Equivalent-electron quasi-bound resonances......Page 150 6.8 Resonance-averaged cross section......Page 151 6.9 Radiation damping of resonances......Page 153 6.9.1 Differential oscillator strength......Page 154 6.9.3 Resonance profiles......Page 155 6.9.4 Shape and Feshbach resonances......Page 157 6.10 Angular distribution and asymmetry......Page 158 7 Electron–ion recombination......Page 161 7.2 Total electron–ion recombination rate......Page 162 7.3.2 Dielectronic recombination......Page 163 7.3.2.1 Quantum probability......Page 166 7.4.1 Rate coefficients......Page 167 7.4.2 Level-specific rate coefficients......Page 168 7.4.3 DR cross sections......Page 169 7.4.4 Multiple resonant features......Page 172 7.4.5 Comparison between experiment and theory......Page 173 7.5 Photorecombination and dielectronic recombination......Page 177 7.6.1 Temperature diagnostics......Page 178 7.6.2 Dielectronic satellite line strengths......Page 181 7.6.2.1 Correspondence between isolated and unified approximations......Page 182 7.8 Ionization equilibrium......Page 183 7.8.1 Photoionization equilibrium......Page 185 7.8.2 Collisional equilibrium......Page 186 7.9 Effective recombination rate coefficient......Page 187 7.10 Plasma effects......Page 188 8 Multi-wavelength emission spectra......Page 189 8.1.1 Atomic rates and lifetimes......Page 190 8.1.2 Collisional and radiative rates......Page 191 8.2 Collisional-radiative model......Page 192 8.3.1 Optical lines: [OII], [SII], [OIII]......Page 193 8.3.1.1 Density dependence of [O II] and [S II] lines......Page 194 8.3.2 Hydrogen and helium recombination lines......Page 196 8.4.1 Density diagnostic ratio R = f / i......Page 197 8.4.3 Electron impact excitation of X-ray lines......Page 198 8.4.4 R and G ratios with fine structure......Page 200 8.4.5 Transient X-ray sources......Page 201 8.5 Far-infrared lines: the boron isoelectronic sequence......Page 205 9.1 Optical depth and column density......Page 208 9.2 Line broadening......Page 209 9.2.1 Natural radiation damping......Page 210 9.2.1.1 Damping constant and classical oscillator......Page 211 9.2.2 Doppler broadening......Page 212 9.2.3 Collisional broadening......Page 213 9.2.3.1 The classical impact approximation......Page 214 9.2.3.3 The nearest-neighbour approximation......Page 215 9.2.3.4 The Holtsmark distribution......Page 216 9.2.3.5 Debye screening potential......Page 217 9.2.3.6 Electron impact broadening......Page 218 9.3 Absorption lines......Page 219 9.3.1 Equivalent width......Page 220 9.3.2 Curve of growth......Page 222 9.4 Radiative transfer......Page 223 9.4.1 Intensity and flux......Page 224 9.4.2 Transfer equation and the source function......Page 225 9.4.4 The two-level atom......Page 226 9.4.5 Scattering......Page 227 9.4.6 Plane-parallel approximation......Page 228 9.4.8 The lambda-operator......Page 229 9.5.2 Boltzmann equation......Page 230 9.5.3 Saha equation......Page 231 9.5.4 Non-LTE rate equation and equation-of-state......Page 232 10.1 Luminosity......Page 234 10.2 Spectral classification – HR diagram......Page 235 10.3 Stellar population – mass and age......Page 238 10.5 Colour, extinction and reddening......Page 239 10.6 Stellar structure and evolution......Page 240 10.6.3 White dwarfs......Page 242 10.6.6 Pulsating stars......Page 243 Novae and Type Ia supernovae......Page 244 10.8 Atmospheres......Page 245 10.9.1 Photosphere......Page 246 10.9.4 Solar corona......Page 249 10.10 Cool and hot stars......Page 250 10.11 Luminous blue variables......Page 251 11.1 Radiative and convective envelope......Page 253 11.2 Equations of stellar structure......Page 254 11.3.1 Diffusion approximation......Page 255 11.4.1 Equation-of-state......Page 257 11.4.1.1 Partition function and occupation probability......Page 258 11.4.2 Radiative atomic processes......Page 260 11.4.2.3 Free–free transitions: inverse bremsstrahlung......Page 261 11.4.3 Monochromatic opacities......Page 262 11.4.4 Abundances, mixtures and atomic data......Page 263 11.5 Radiative forces and levitation......Page 266 11.5.1 Atomic processes and momemtum transfer......Page 267 11.5.2 Radiative acceleration......Page 268 11.6 Opacities and accelerations database......Page 269 12.2 Physical model and atomic species......Page 271 12.3 Ionization structure......Page 273 12.4 Spectral diagnostics......Page 275 12.4.1.1 Case A and Case B recombination......Page 276 12.4.1.2 Cascade coefficients and emissivities......Page 277 12.4.2 Departures from LTE......Page 278 12.4.3 Collisional excitation and photoionization rates......Page 279 12.4.4.1 [FeII] lines......Page 280 12.4.4.3 [Fe IV] lines......Page 283 12.5.2 Continuum fluorescence......Page 286 12.5.2.1 Fluorescence of Ni II......Page 287 12.6 Abundance analysis......Page 289 12.7 Atomic parameters for nebular emission lines......Page 291 13 Active galactic nuclei and quasars......Page 292 13.1 Morphology, energetics and spectra......Page 293 13.1.2 Supermassive black holes: the central engines......Page 295 13.1.4 The M.–sigma relation......Page 298 13.1.6 States of black hole activity......Page 299 13.1.7 Radio intensity......Page 301 13.2 Spectral characteristics......Page 302 13.3 Narrow-line region......Page 304 13.5 Fe II spectral formation......Page 305 13.5.1 Fe II Excitation Mechanisms......Page 306 13.5.2 Fe I–Fe III emission line strengths......Page 307 13.5.3 Spectral properties and the central source......Page 308 13.6 The central engine – X-ray spectroscopy......Page 309 13.6.1 Fe Kalpha X-ray lines and relativistic broadening......Page 310 13.6.2 Warm absorber (WA)......Page 313 13.6.4 L-shell lines......Page 314 13.6.5 K-shell lines......Page 316 14 Cosmology......Page 319 14.1 Hubble expansion......Page 320 14.2 Recombination epoch......Page 321 14.3 Reionization and Lyα forests......Page 322 14.3.1 Damped Lyman alpha systems......Page 323 14.4 CMB anisotropy......Page 324 14.5 Helium abundance......Page 326 14.6 Dark matter: warm–hot intergalactic medium......Page 327 14.7 Time variation of fundamental constants......Page 328 14.8.1 Parallax......Page 330 14.8.3 Cepheid distance scale......Page 331 14.8.4 Rotation velocity and luminosity......Page 332 14.8.5 Supernovae......Page 333 14.8.6 Acceleration of the Universe and dark energy......Page 336 Appendix A Periodic table......Page 338 Appendix B Physical constants......Page 339 C.1 3-j symbols......Page 342 C.3 Vector and tensor components......Page 343 C.4 Generalized radiative transitions......Page 344 Appendix D Coefficients of the fine structure components of an LS multiplet......Page 347 Appendix E Effective collision strengths and A-values......Page 351 References......Page 362 Index......Page 371 "Spectroscopy enables the precise study of astronomical objects and phenomena. Bridging the gap between physics and astronomy, this is the first integrated graduate-level textbook on atomic astrophysics. It covers the basics of atomic physics and astrophysics, including state-of-the-art research applications, methods and tools. The content is evenly balanced between the physical foundations of spectroscopy and their applications to astronomical objects and cosmology. An undergraduate knowledge of physics is assumed, and relevant basic material is summarised at the beginning of each chapter. The material is completely self-contained and features sufficient background information for self-study. Advanced users will find it handy for spectroscopic studies. A website hosted by the authors contains updates, corrections, exercises and solutions, as well as news items from physics and astronomy related to spectroscopy. A link to this can be found at www.cambridge.org/9780521825368"--. - "The text is evenly divided into atomic physics and astrophysics. The first seven chapters form the foundational elements of atomic processes and spectroscopy. The next seven chapters deal with astrophysical applications to specific objects and physical conditions. Each chapter follows the same plan. We begin with the essentials that all readers should be able to follow easily. However, towards the end of each chapter we outline some of the more advanced or specialized areas. The subject matter is broadly divided into 'basic' material in both areas, and 'advanced' material that incorporates state-of-the-art methods and results." Spectroscopy enables the precise study of astronomical objects and phenomena. Bridging the gap between physics and astronomy, this is the first integrated graduate-level textbook on atomic astrophysics. It covers the basics of atomic physics and astrophysics, including state-of-the-art research applications, methods and tools. The content is evenly balanced between the physical foundations of spectroscopy and their applications to astronomical objects and cosmology. An undergraduate knowledge of physics is assumed, and relevant basic material is summarised at the beginning of each chapter. The material is completely self-contained and features sufficient background information for self-study. Advanced users will find it handy for spectroscopic studies. A website hosted by the authors contains updates, corrections, exercises and solutions, as well as news items from physics and astronomy related to spectroscopy. A link to this can be found at (http://www.cambridge.org/9780521825368) www.cambridge.org/9780521825368 . "The text is evenly divided into atomic physics and astrophysics. The first seven chapters form the foundational elements of atomic processes and spectroscopy. The next seven chapters deal with astrophysical applications to specific objects and physical conditions. Each chapter follows the same plan. We begin with the essentials that all readers should be able to follow easily. However, towards the end of each chapter we outline some of the more advanced or specialized areas. The subject matter is broadly divided into 'basic' material in both areas, and 'advanced' material that incorporates state-of-the-art methods and results"-- Provided by publisher Machine Generated Contents Note: 1. Introduction; 2. Atomic Structure; 3. Atomic Processes; 4. Radiative Transitions; 5. Electron-ion Collisions; 6. Photoionization; 7. Electron-ion Recombination; 8. Multi-wavelength Emission Spectra; 9. Absorption Lines And Radiative Transfer; 10. Stellar Properties And Spectra; 11. Stellar Opacity And Radiative Forces; 12. Gaseous Nebulae And Hii Regions; 13. Active Galactic Nuclei And Quasars; 14. Cosmology; Appendices; References; Index. Anil K. Pradhan And Sultana N. Nahar. Includes Bibliographical References And Index.