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) At an undergraduate-only college (1500 students in total; 15 physics majors per class year; >50% to Ph. D programs) (I have done some work in ICF and lab astro, too)

Small liberal arts colleges disproportionately produce students who go on to earn physics Ph. Ds 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

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

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

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

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

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

Ionization parameter – describes physical conditions x = L/r 2 n (ergs cm s-1) Ranges from 100 to 10, 000 (cgs units)

ASCA (Japan) – state of the art 1999

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

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

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

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?

Extragalactic sources: Active Galactic Nuclei (AGN)

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

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

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

Photoionization experiments on the Z-Machine

1018 cm-3 of neon

spectrometer view gas supply gas cell 1. 5 mm mylar pinch

spectrometer view 1. 5 mm mylar pinch gas supply gas cell Side view with second spectrometer – measure recombination spectrum

View-factor (Vis. Rad: Prism) model (Mac. Farlane et al. ) constructed by Swarthmore undergraduate, M. Rosenberg

Genetic algorithm – forward modeling to extract CSD

Complementary: Curve of Growth analysis (in progress)

We model the CSD with Prism. Spect and with CLOUDY Adjust incident spectrum to match experimental results with simulations

We model the CSD with Prism. Spect and 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%

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

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

Laboratory Astrophysics Needs wavelengths & oscillator strengths • Wind speeds are largely of a few 100 km/s => – Required wavelength accuracy thus < 1/1000 (< 2 - 20 mÅ) • Atomic codes hardly achieve such accuracy • How reliable are the computed photo-absorption cross sections ~ fij ? Courtesy: E. Behar

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

Difficulties If lab system is integrated (e. g. hydro important in the photoionization experiments) it’s never in the way that’s relevant to integrated astrophysical problem. Regimes are difficult to match (e. g. densities too high). Timescales and equilibrium. Sociological/communication issues – delivering the information astrophysicists already (know they) want.

Needs and future prospects Specifically for photoionization experiments More X-ray power/flux and higher ionization parameters

Needs and future prospects Specifically for photoionization experiments More X-ray power/flux and higher ionization parameters More and better diagnostics

spectrometer view 1. 5 mm mylar pinch gas supply gas cell Side view with second spectrometer – measure recombination spectrum

Needs and future prospects Specifically for photoionization experiments More X-ray power/flux and higher ionization parameters More and better diagnostics Different materials (e. g. iron, but gaseous ? ) Are there relevant experiments that can be done at NIF?

Launched 2000: superior sensitivity, spatial resolution, and spectral resolution Chandra XMM-Newton sub-arcsecond resolution

XMM-Newton Both have CCD detectors for imaging spectroscopy: low spectral resolution: R ~ 20 to 50 Chandra And both have grating spectrometers: R ~ few 100 to 1000 300 km/s

XMM-Newton The gratings have poor sensitivity… We’ll never get spectra for more than a handful of any particular class of object Chandra

XMM-Newton Chandra The Future: Astro-H (Japan) – high spectral resolution at high photon energies …few years from now: 2 e. V at 7 ke. V (microcalorimeter array) International X-ray Observatory (IXO; US&Europe)… ~ 2020 Focus on iron K-shell

Conclusions X-ray photoionization experiments are producing results …higher X-ray fluxes (and ionization parameters) are required for direct astrophysical relevance.

Comments on some other lab astro experiments

38 citations to the Shigemori et al. jets paper…none are traditional astronomy

transmission The OP model used in solar research predicts Fe Lshell opacity that is too low at Z conditions 0. 8 0. 6 Red= Z data Blue=OP c 2 = 16 0. 4 0. 8 0. 6 Red= Z data Blue=OPAS c 2 = 3. 7 0. 4 0. 2 1000 1100 hn (e. V) 1200 1300 OP Rosseland mean is ~ 1. 5 x lower than OPAS at Z conditions. If this difference persisted at solar conditions, it would solve the CZ problem Courtesy: J. Bailey

Some related thoughts

Helium heating-cooling balance is very important… …so isolating one element at a time is also problematic.

Interesting and relevant systems aren’t always in the HED regime

opacity (cm 2/g) UV spectrum: C IV 1548, 1551 Å radius v∞=2350 km/s Velocity (km/s) Prinja et al. 1992, Ap. J, 390, 266 Luminosity (ergs/s)

1 -D rad-hydro simulation of a massive star wind Radiation line driving is inherently unstable: shock-heating and X-ray emission

Chandra HETGS/MEG spectrum (R ~ 1000 ~ 300 km s-1) Si H-like He-like Mg Ne Fe Pup O

1 -D rad-hydro simulation of a massive star wind We can study clumping in these winds by watching them be blasted by x-rays from a compact object

Swarthmore Spheromak Experiment (SSX) k. T ~ 50 e. V; ne ~ 1014; B ~ 0. 1 T

Student training and exposure to HED concepts, techniques

Conclusions X-ray photoionization experiments are producing results …higher X-ray fluxes (and ionization parameters) are required for direct astrophysical relevance.