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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)
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
pinchpinch
spectrometerspectrometerviewview
gasgassupplysupply
1.5 1.5 m m mylarmylar
gas cellgas cell
pinchpinch
spectrometerspectrometerviewview
gasgassupplysupply
1.5 1.5 m m mylarmylar
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
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
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
spectrometerspectrometerviewview
gasgassupplysupply
1.5 1.5 m m mylarmylar
gas cellgas cell
Side view with second spectrometer – measure Side view with second spectrometer – measure recombination spectrumrecombination spectrum
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
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
XMM-NewtonXMM-Newton
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
XMM-NewtonXMM-Newton
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
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
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