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Photoionized Plasmas: Connections Between Laboratory and Astrophysical Plasmas

Photoionized Plasmas: Connections Between Laboratory and Astrophysical Plasmas. David Cohen Swarthmore College. Collaboration with R. Mancini, J. Bailey, G. Rochau. My background/perspective: Traditional astrophysicist (massive stars, their winds, and x-ray emission)

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Photoionized Plasmas: Connections Between Laboratory and Astrophysical Plasmas

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  1. Photoionized Plasmas: Connections Between Laboratory and Astrophysical Plasmas David CohenSwarthmore College Collaboration with R. Mancini, J. Bailey, G. Rochau

  2. My background/perspective: • Traditional astrophysicist (massive stars, their winds, and x-ray emission) • At an undergraduate-only college (1500 students in total; 15 physics majors per class year; >50% to PhD programs) (I have done some work in ICF and lab astro, too)

  3. Small liberal arts colleges disproportionately produce students who go on to earn physics PhDs e.g. Bill Goldstein, John Mather are Swarthmore College alumni My own students: Amy Reighard (2001) – Michigan – LLNL Vernon Chaplin (2007) – Caltech Mike Rosenberg (2008) – MIT

  4. We study black holes (and neutron stars) by watching material fall onto them Hard x-rays from accretion photoionize surrounding (accreting) material – we need to interpret the spectra Broad (astro) science goals: Compact object and accretion physics Physical conditions in the stellar winds/mass-flows Stellar evolution and populations Astrophysical jets Galactic structure Effect of super-massive black hole “feedback” on large scale structure formation

  5. Large Scale Structure of the Universe: Gravity from dark matter And Energy injection from AGN (“feedback”) Millennium simulation

  6. High-Mass X-ray Binary (HMXRB): Direct wind accretion onto a stellar mass compact object

  7. Active Galactic Nucleus (AGN): accretion onto a ~109 Msun black hole M 82 – red is X-ray emission

  8. Iron models with same ionization balance – very different emission properties (coronal: left and photoionized: right)

  9. Ionization parameter – describes physical conditions x = L/r2n (ergs cm s-1) Ranges from 100 to 10,000 (cgs units)

  10. ASCA (Japan) – state of the art 1999

  11. Distribution of plasma vs. ionization parameter Peak at low values indicates high-density clumps

  12. Chandra (US) state of the art today Low ionization state satellites – fluorescence in high-density clumps

  13. Mauche et al. 2008, “The Physics of Wind-Fed Accretion”

  14. DEM of x distribution (combined with modeling): Wind density and inhomogeneity (clumping) Dynamics and accretion Ionization and feedback on the dynamics Broadly: How will this system evolve? When we find other systems with quantitative differences in their x-ray spectra, what can we infer about their physical properties?

  15. Extragalactic sources: Active Galactic Nuclei (AGN)

  16. Challenges • Scaling – e.g. in photoionized sources: • Low densities (else collisional); but then equilibration? • Significant optical depths (else RT effects not accounted for) • Thus, large linear scales – incompatible with the lab

  17. Challenges • Systems are integrated: • Gravity • Hydro • Atomic physics • Excitation/ionization kinetics • Radiation transport

  18. Obvious astrophysical relevance is easiest to realize and demonstrate when: • Measurements are local • Small subset of an integrated problem is probed

  19. Photoionization experiments on the Z-Machine

  20. 1018 cm-3 of neon

  21. 1.5 mm mylar spectrometer view pinch gas supply gas cell

  22. 1.5 mm mylar spectrometer view pinch gas supply gas cell Side view with second spectrometer – measure recombination spectrum

  23. View-factor (VisRad: Prism) model (MacFarlane et al.) constructed by Swarthmore undergraduate, M. Rosenberg

  24. Genetic algorithm – forward modeling to extract CSD

  25. Complementary: Curve of Growth analysis (in progress)

  26. We model the CSD with PrismSpectand with CLOUDY Adjust incident spectrum to match experimental results with simulations

  27. We model the CSD with PrismSpectand with CLOUDY Adjust incident spectrum to match experimental results with simulations Both codes reproduce the CSD, but with different radiation fields – the calculated ionization parameters differ by 50%

  28. Connections to astrophysics Code benchmarking – what CSD, temperature arise from a given ionization parameter? Atomic physics – wavelengths, line broadening, even line identification

  29. Controversy: broad Fe UTA or O K-shell edge?

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