Photoionized Plasmas: Connections Between Laboratory and Astrophysical Plasmas

Photoionized Plasmas: Connections Between Photoionized Plasmas: Connections Between Laboratory and Astrophysical PlasmasLaboratory and Astrophysical Plasmas

David CohenDavid CohenSwarthmore CollegeSwarthmore College

Collaboration with R. Mancini, J. Bailey, G. RochauCollaboration with R. Mancini, J. Bailey, G. Rochau

My background/perspective: My background/perspective:

Traditional astrophysicist (massive stars, their Traditional astrophysicist (massive stars, their winds, and x-ray emission)winds, and x-ray emission)

At an undergraduate-only college (1500 students in At an undergraduate-only college (1500 students in total; 15 physics majors per class year; >50% to total; 15 physics majors per class year; >50% to PhD programs)PhD programs)

(I have done some work in ICF and lab astro, too)(I have done some work in ICF and lab astro, too)

Small liberal arts colleges disproportionately produce Small liberal arts colleges disproportionately produce students who go on to earn physics PhDsstudents who go on to earn physics PhDs

e.g. Bill Goldstein, John Mather are Swarthmore e.g. Bill Goldstein, John Mather are Swarthmore College alumniCollege alumni

My own students: My own students:

Amy Reighard (2001) – Michigan – LLNL Amy Reighard (2001) – Michigan – LLNL Vernon Chaplin (2007) – CaltechVernon Chaplin (2007) – CaltechMike Rosenberg (2008) – MIT Mike Rosenberg (2008) – MIT

We study black holes (and neutron stars) by watching We study black holes (and neutron stars) by watching material fall onto themmaterial fall onto them

Hard x-rays from accretion photoionize surrounding Hard x-rays from accretion photoionize surrounding (accreting) material – we need to interpret the spectra (accreting) material – we need to interpret the spectra

Broad (astro) science goals: Broad (astro) science goals:

Compact object and accretion physicsCompact object and accretion physicsPhysical conditions in the stellar winds/mass-flowsPhysical conditions in the stellar winds/mass-flowsStellar evolution and populationsStellar evolution and populationsAstrophysical jetsAstrophysical jetsGalactic structureGalactic structureEffect of super-massive black hole “feedback” on large Effect of super-massive black hole “feedback” on large scale structure formationscale structure formation

Large Scale Large Scale Structure of the Structure of the Universe: Universe:

Gravity from dark Gravity from dark matter matter

AndAnd

Energy injection Energy injection from AGN from AGN (“feedback”)(“feedback”)

Millennium simulation Millennium simulation

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

Active Galactic Nucleus (AGN): Active Galactic Nucleus (AGN): accretion onto a ~10accretion onto a ~1099 M Msunsun black hole black hole

M 82 – red is X-ray emissionM 82 – red is X-ray emission

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

Ionization parameter – describes physical conditionsIonization parameter – describes physical conditions

= L/r= L/r22n (ergs cm sn (ergs cm s-1-1))

Ranges from 100 to Ranges from 100 to 10,000 (cgs units)10,000 (cgs units)

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

Distribution of plasma vs. ionization parameterDistribution of plasma vs. ionization parameter

Peak at low values indicates high-density clumps Peak at low values indicates high-density clumps

Chandra Chandra (US) state of the art today(US) state of the art today

Low ionization state satellites – fluorescence Low ionization state satellites – fluorescence in high-density clumpsin high-density clumps

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

DEM of DEM of distribution (combined with modeling): distribution (combined with modeling):

Wind density and inhomogeneity (clumping)Wind density and inhomogeneity (clumping)Dynamics and accretionDynamics and accretionIonization and feedback on the dynamics Ionization and feedback on the dynamics

Broadly: Broadly:

How will this system evolve?How will this system evolve?

When we find other systems with quantitative When we find other systems with quantitative differences in their x-ray spectra, what can we differences in their x-ray spectra, what can we infer about their physical properties?infer about their physical properties?

Extragalactic sources: Active Galactic Nuclei (AGN)Extragalactic sources: Active Galactic Nuclei (AGN)

ChallengesChallenges

Scaling – e.g. in photoionized sources: Scaling – e.g. in photoionized sources:

•Low densities (else collisional); but then equilibration?Low densities (else collisional); but then equilibration?•Significant optical depths (else RT effects not Significant optical depths (else RT effects not accounted for)accounted for)•Thus, large linear scales – incompatible with the labThus, large linear scales – incompatible with the lab

ChallengesChallenges

Systems are integrated: Systems are integrated:

•GravityGravity•HydroHydro•Atomic physicsAtomic physics•Excitation/ionization kineticsExcitation/ionization kinetics•Radiation transportRadiation transport

Obvious astrophysical relevance is easiest to realize Obvious astrophysical relevance is easiest to realize and demonstrate when: and demonstrate when:

•Measurements are local Measurements are local •Small subset of an integrated problem is probedSmall subset of an integrated problem is probed

Photoionization experiments on the Photoionization experiments on the Z-MachineZ-Machine

10101818 cm cm-3-3 of neon of neon

pinchpinch

spectrometerspectrometerviewview

gasgassupplysupply

1.5 1.5 m m mylarmylar

gas cellgas cell

pinchpinch


gasgassupplysupply


gas cellgas cell

Side view with second spectrometer – measure Side view with second spectrometer – measure recombination spectrumrecombination spectrum

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

Genetic algorithm – forward modeling to extract CSDGenetic algorithm – forward modeling to extract CSD

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

We model the CSD with We model the CSD with PrismSpect PrismSpect and with and with CLOUDYCLOUDY

Adjust incident spectrum to match experimental Adjust incident spectrum to match experimental results with simulationsresults with simulations

We model the CSD with We model the CSD with PrismSpect PrismSpect and with and with CLOUDYCLOUDY

Adjust incident spectrum to match experimental Adjust incident spectrum to match experimental results with simulationsresults with simulations

Both codes reproduce the CSD, but with different Both codes reproduce the CSD, but with different radiation fields – radiation fields – the calculated ionization the calculated ionization parameters differ by 50%parameters differ by 50%

Connections to astrophysicsConnections to astrophysics

Code benchmarking – what CSD, temperature Code benchmarking – what CSD, temperature arise from a given ionization parameter? arise from a given ionization parameter?

Atomic physics – wavelengths, line broadening, Atomic physics – wavelengths, line broadening, even even line identificationline identification

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

Laboratory Astrophysics Needswavelengths & 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. BeharCourtesy: E. Behar

Connections to astrophysicsConnections to astrophysics

Code benchmarking – what CSD, temperature Code benchmarking – what CSD, temperature arise from a given ionization parameter? arise from a given ionization parameter?

Atomic physics – wavelengths, line broadening, Atomic physics – wavelengths, line broadening, even even line identificationline identification

DifficultiesDifficulties

If lab system is integrated (e.g. hydro important in If lab system is integrated (e.g. hydro important in the photoionization experiments) it’s never in the the photoionization experiments) it’s never in the way that’s relevant to integrated astrophysical way that’s relevant to integrated astrophysical problem.problem.

Regimes are difficult to match (e.g. densities too Regimes are difficult to match (e.g. densities too high).high).

Timescales and equilibrium.Timescales and equilibrium.

Sociological/communication issues – delivering the Sociological/communication issues – delivering the information astrophysicists already (know they) information astrophysicists already (know they) want. want.

Needs and future prospectsNeeds and future prospects

Specifically for photoionization experimentsSpecifically for photoionization experiments

More X-ray power/flux and higher ionization parametersMore X-ray power/flux and higher ionization parameters




More and better diagnostics More and better diagnostics

pinchpinch


gasgassupplysupply


gas cellgas cell

Side view with second spectrometer – measure Side view with second spectrometer – measure recombination spectrumrecombination spectrum




More and better diagnostics More and better diagnostics

Different materials (e.g. iron, but gaseous ?)Different materials (e.g. iron, but gaseous ?)

Are there relevant experiments that can be Are there relevant experiments that can be done at NIF? done at NIF?

XMM-NewtonXMM-Newton

ChandraChandraLaunched 2000: superior Launched 2000: superior

sensitivity, sensitivity, spatial resolution, and spatial resolution, and spectral resolutionspectral resolution

sub-arcsecond resolutionsub-arcsecond resolution


ChandraChandra

Both have CCD detectors for Both have CCD detectors for imaging spectroscopy:imaging spectroscopy:

low spectral resolution: low spectral resolution: R R ~ 20 to 50~ 20 to 50

And both have grating And both have grating spectrometers: spectrometers: R R ~ few 100 to 1000~ few 100 to 1000

300 km/s300 km/s


ChandraChandra

The The gratings gratings have have poor sensitivitypoor sensitivity……We’ll never get spectra for more We’ll never get spectra for more than a handful of any particular than a handful of any particular class of objectclass of object

Astro-HAstro-H (Japan) – high spectral (Japan) – high spectral resolution at high photon energiesresolution at high photon energies……few years from now: few years from now: 2 eV at 7 keV (microcalorimeter array)2 eV at 7 keV (microcalorimeter array)

International X-ray Observatory International X-ray Observatory (IXO; (IXO; US&Europe)… ~ 2020US&Europe)… ~ 2020

The Future:The Future:

Focus on iron K-shellFocus on iron K-shell

X-ray photoionization experiments are producing resultsX-ray photoionization experiments are producing results

……higher X-ray fluxes (and ionization parameters) are higher X-ray fluxes (and ionization parameters) are required for direct astrophysical relevance. required for direct astrophysical relevance.

ConclusionsConclusions

Comments on some other lab astro experimentsComments on some other lab astro experiments

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

The OP model used in solar research predicts Fe L-The OP model used in solar research predicts Fe L-shell opacity that is too low at Z conditions shell opacity that is too low at Z conditions

10001000 11001100 12001200 130013000.20.2

0.40.4

0.60.6

0.80.8

hh (eV) (eV)

Red= Z dataRed= Z dataBlue=OPBlue=OP22 = 16 = 16

Red= Z dataRed= Z dataBlue=OPASBlue=OPAS22 = 3.7 = 3.7tr

ansm

issi

ontr

ansm

issi

ontr

ansm

issi

ontr

ansm

issi

on

0.40.4

0.60.6

0.80.8

OP Rosseland mean is ~ 1.5x lower than OPAS at Z conditions.OP Rosseland mean is ~ 1.5x lower than OPAS at Z conditions.If this difference persisted at solar conditions, it would solve the CZ problemIf this difference persisted at solar conditions, it would solve the CZ problem

Courtesy: J. BaileyCourtesy: J. Bailey

Some related thoughtsSome related thoughts

Helium heating-cooling Helium heating-cooling balance is very balance is very important…important…

……so isolating one so isolating one element at a time is element at a time is

also problematic.also problematic.

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

Prinja et al. 1992, ApJ, 390, Prinja et al. 1992, ApJ, 390, 266266Velocity (km/s)Velocity (km/s)

v∞=2350 km/s

UV spectrum: C IV 1548, 1551 ÅUV spectrum: C IV 1548, 1551 Å€

arad =κL

4πR2c

Luminosity (ergs/s)Luminosity (ergs/s)opacity (cmopacity (cm22/g)/g)

radiusradius

1-D rad-hydro simulation of a massive star wind1-D rad-hydro simulation of a massive star wind

Radiation Radiation line driving line driving is inherently unstable: is inherently unstable: shock-heating and X-ray emissionshock-heating and X-ray emission

PupPup

Chandra Chandra HETGS/MEG spectrum HETGS/MEG spectrum ((RR ~ 1000 ~ 300 km s ~ 1000 ~ 300 km s-1-1))

SiSi MgMg NeNe OOFeFe

H-likeH-likeHe-likeHe-like

1-D rad-hydro simulation of a massive star wind1-D rad-hydro simulation of a massive star wind

We can study clumping in these winds by watching We can study clumping in these winds by watching them be blasted by x-rays from a compact objectthem be blasted by x-rays from a compact object

Swarthmore Spheromak Experiment (SSX)Swarthmore Spheromak Experiment (SSX)

kT ~ 50 eV; nkT ~ 50 eV; nee ~ 10 ~ 101414; B ~ 0.1 T; B ~ 0.1 T

Student training and exposure to HED concepts, Student training and exposure to HED concepts, techniquestechniques

X-ray photoionization experiments are producing resultsX-ray photoionization experiments are producing results

……higher X-ray fluxes (and ionization parameters) are higher X-ray fluxes (and ionization parameters) are required for direct astrophysical relevance. required for direct astrophysical relevance.

ConclusionsConclusions

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Photoionized Plasmas: Connections Between Laboratory and Astrophysical Plasmas