Outline. Great X-Ray Observatories. a ThousandPictures. CCD Spectral Resolution & Discerning Orders. X-Ray Grating Spectrometers

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1 SPECTROCOPIC DIAGNOSTICS OF ASTROPHYSICAL PLASMAS b. c. d. IAEA Advanced School on Plasma Spectroscopy ICTP, March 2015 Chandra Observatory (NASA): XMM-Newton (ESA): Smaller Scale Telescopes Coronal Elemental Fractionation Cold recombination and Collisionless Shocks Absorption of black hole winds Probing the missing baryons of the universe A Spectrum isworth Worth A Picture is a Thousand a ThousandPictures Words? Great X-Ray Observatories X-Ray Space Spectrometers superb telescope (0.5 ) eff. area = 4,300 cm2 vs. Suzaku (JAXA) Swift (γ-ray, NASA + co.) Both have CCD spectrometers NuSTAR hard-x imager > 70 kev Future (projected launch) erosita (2015) all sky survey < 10 kev Astro-H (2016) w/ calorimeter ATHENA (20??) CCD Spectral Resolution & Discerning Orders X-Ray Grating Spectrometers Transmission (Chandra) d (Sinβ + Sinα) = mλ dλ/dβ = d Cosβ ~ d Reflection (XMM-Newton) d (Cosβ - Cosα) = mλ dλ/dβ = d Sinβ << d Capella Flux (arb. units) α is the (small) incidence angle Astro-H Non-Dispersive Calorimeter Spectrometer Japanese Mission + NASA collaboration Spectroscopy mission with superconducting microcalorimeter as the main science instrument Hard X-Ray (5-80 kev) imager on 12m extendable bench Projected launch early 2016 Chandra/HETGS 5 10 Wavelength (Å) High Effective Area of Non-Dispersive Spectrometer

2 Resolving Power E/ E = / X-Ray Space Spectrometers Coronal Elemental Fractionation b. Cold recombination and Collisionless Shocks c. Absorption of black hole winds d. Probing the missing baryons of the universe Stellar Coronae Measuring Elemental Abundances Outer atmosphere of cool stars Much hotter MKs vs. kks and more tenuous 10 9 cm -3 vs cm -3 than stellar photosphere Solar coronal activity responsible for space weather, such as electromagnetic storms on Earth aurora (northern lights) global warming How much do we really understand the Sun? Line transition from upper level j to lower level i Intensity (ph s -1 cm -3 ) emitted in plasma I ji = n j A ji Recast n j n j = (n j /n q ) (n q /n Z ) (n Z /n H )n H = (n j /n q ) f q (T) A Z n gas Relative abundances are easy, absolute n Z /n H comes from bremsstrahlung Flux (arb. units) Capella Chandra/HETGS Wavelength (Å) What Causes Abundance Fractionation in Stellar Coronae? In More Active Stars Inverse FIP Effect Solar FIP effect (first ionization potential): Low-FIP elements are enriched in the solar corona (and in solar wind) by 3-4 compared to the photosphere Coronal enrichment relative to solar photosphere Steiger et al First Ionization Potential (ev) Inverse FIP effect in HR 1099 Mg Ni Fe S C N O Ne Are Coronal Flares Driving the FIP / IFIP Effect? FIP Bias = <loga Z (lowfip)> - <loga Z (highfip)> Does flare behavior depend on coronal FIP? Low FIP enrichment during flares on active stars Solar flares show high-fip enrichment Emerging trend: Bias during flare tends to the chromospheric composition, opposite of quiescent FIP Chromospheric Evaporation, but flares do not drive FIP Note the errors More low-fip (solar corona)

3 Do Photospheric Abundances Drive the FIP Effect? Abundance Ni Si Mg Fe alpha Centauri B C O N Ne Current and Future Space Spectrometers Coronal Elemental Fractionation b. Cold recombination and Collisionless Shocks c. X-ray absorption and Black Hole winds d. Probing the missing baryons of the universe Planetary Nebulae 1D Radial Profiles fast wind hot bubble Density shocked cold nebula nebula conduction? Temp. X-Rays * Collisionless Shocks Hot (~100 ev) Emission The Discovery is in the Details Sharp jump conditions are assumed But, mean free path is immense ~ nebular size M λ mfp = v w t s w cm Z w Magnetic fields could sustain jump conditions of shock and contact discontinuity, but no direct evidence Magnetic fields would inhibit conduction/evaporation All these are very hard to study directly and therefore usually left in the realm of theory Can we obtain further insights from X-ray spectrum? Z n n n M C Narrow (Cold e - ) C +6 Radiative Recombination Continuum RRCs Common to Photo-ionized Plasmas Recombination of hot ions (~100 ev) with cold electrons (~ 1 ev) RRC width => kt e = 1.7 ± 1.3 ev Intermediate temperatures 3 ev < kt < 100 ev can not be significant Origin? Flux (photons sec -1 Å -1 cm -2 ) NGC 1068 RGS / XMM-Newton C VI Lyα line C V RRC at 3 ev Wavelength (Å)

4 What Can Explain The Narrow RRC? 100 ev (shocked?) fast wind ions interact hot bubble directly with 1 ev (un-shocked?) electrons, but where? Natural Location: Contact Discontinuity, but can ions cross? shocked cold Microphysics around CD is complicated. nebula nebula assuming a magnetic field and mere thermal motion: evaporation? τlarmor 650 (M/MC)(B/1μG)-1 s τslowdown 1000 (ktcool/1ev)3/2(ncool/104cm-3)-1 s (by e-, p) τrec 2x107 (ktcool/1ev)1/2(ne/104cm-3)-1 s Ions cross, slow down, & only much later recombine Intermediate-temperature X-Rays region (say 10 ev) can not be large, or ions would stop and recombine before reaching 1 ev region ; Δrinter < vionτs (10 ev) 109 cm. In contrast with smooth gradient expected from heat conduction. * More Diagnostics RRC intensity (1040 ph/s): Mass crossing rate of 4x10-8 M /yr ~ 10% wind From upper limit on C VI to C VII RRC flux ratio, very conservative hot-side temp. estimate kthot > 84 ev, i.e., ΔkT across CD > 80 ev Note: RRC contribution to total flux is miniscule: 33 RRC photons (~1/10ks), 300 words/photon in paper few $K / RRC photon in CXC grant Active Galaxies / Quasars X-Ray Space Spectrometers b. c. d. Coronal Elemental Fractionation Cold recombination and Collisionless Shocks Absorption of black hole winds Probing the missing baryons of the universe Active Galaxy Outflows: Splattering Blenders 6 Telescopes Observing One Black Hole Wind Outflows studied by their absorption of nuclear source Fast moving photo-ionized plasma Measuring Absorption: It is What You Don t See that Counts X-Ray Space Spectrometers b. c. d. Coronal Elemental Fractionation Cold recombination and Collisionless Shocks Absorption of black hole winds X-ray absorption by the missing baryons of the universe

5 The Missing Atoms (Baryons) of The Universe Cosmic Web and Missing Baryon Problem From CMB and Big-Bang Nucleosynthesis, only 4.6% of the energy content of the Universe is in baryons (atoms)) In the local Universe, only ~50% are accounted for 5% Stars 5% Gas in galaxies, groups, and clusters 40% Intergalactic UV absorption systems Virgo consortium 50% baryons remain missing Telescope Searching for The Missing Baryons by X-Ray Absorption of High-z Sources Some detected through UV spectroscopy Atoms most efficiently absorb soft X-rays through photoionization Available X-Ray spectra are not high resolution Prevalent absorption of gamma ray bursts and quasars has been discovered E (kev) -ln(i/i0) = τ = σ nhds Simulation Excess Extragalactic Column Density - nhdl Swift /XRT Campana Gamma Ray Burst (X-Ray) Afterglows ROSAT Elvis z > 2 Quasars XMM-Newton Swift /XRT Optical Depth Levels Off at High-z τgrb-x (0.5 kev) 0.4 X-Ray Absorption at CCD Resolution Neutral Photo-Ionization Edges Cross section per H-atom sharply decreases with photon energy σpi ~ E-5/2 High-z host column NH has diminished effect at observed energy of Eobs = Eem/(1+z) NH (z)= τ /σ ~ (1+z)5/2 GRB/ QSO τ H,He C N O Fe z τ

6 What Can Produce the Observed τ constant? Neutral, Diffuse, Metal-Rich IGM => Constant Optical Depth Naïve mean cosmological (neutral) opacity standard cosmology baryon (H) density n H = n 0 (1+z ) 3 PI cross section σ(e,z,z 0 ) ~ Z 0 σ (E,0)(1+z ) -5/2 metallicity evolution Z(z )= Z 0 η(z ) = Z 0 (1+z ) -k z τ IGM ( E,z,Z Θ )= n H ( z' )σ ( E,z', Z Θ )c dt ' dz' dz' 0 z n 0 cz 0 ( 1 + z' ) σ ( E,0) 3 η( z' )dz' H 0 0 ( 1 + z' ) 5/2 ( 1+ z' ) ( 1 + z' ) 3 Ω M + Ω Λ ~(1+z ) -2 η(z ) z > 2 Quasar Sanity Check Decreasing Opacity with Ionization z =2.7 He reionization H,He C N O Starling et al Fe-L Ne Mg Si Many More AGNs Starling+ 13 N H (z) ~ (1+z) 2.5? Scott+ 11 (8%) Page+ 05 RQ (Vignali+ 05) RL (Behar+ 11) X-Ray Space Spectrometers Coronal Elemental Fractionation b. Cold recombination and Collisionless Shocks c. Absorption of black hole winds d. X-ray absorption by the missing baryons of the universe Laboratory Astrophysics Needs wavelengths & oscillator strengths Laboratory Astrophys. Methods wavelengths with HETGS Wind speeds of a few 100 km/s => Required wavelength accuracy thus < 1/1000 (< 2-20 må) Atomic codes hardly achieve such accuracy Absorption spectra are hard to obtain in laboratory plasma If nothing else available, we use astrophysical spectra Calculated Corrected How reliable are the computed photo-absorption cross sections σ ~ f ij? Obvious disadvantages: Uncontrolled, Complex kinematics, Chemical impurities

7 Laboratory Astrophysics Methods Portable EBIT + Synchrotron Source Laboratory Astrophysics Methods Z-Machine Photo-ionization of ions in EBIT by monochromatic synchrotron with energy precision as high as E/ΔE = 6000 (19000 with LCLS) Take advantage of autoionizing resonances Disadvantages: measure photo-ionization, collisionally ionized source, limited low charge states Absorption in true steadystate photo-ionized plasma High resolution spectra Capability has been demonstrated for both metal and gas targets Focused so far on ionization balance Disadvantages: high density, but flexibility with position, size, gas pressure (solid pre heating) Foord et al Aiming at Few kev Energies Concluding Remarks -N -C -B -Be -Li -He Astro-H calorimeter simulation of ionized absorber Space-borne X-ray spectrometers provide high precision laboratory-quality spectra Plasma diagnostics are key to understanding X-ray astrophysical sources just as they are in the lab FIP trends in stars measured but remain to be understood Collisionless shocks confirmed in planetary nebula Galactic wind opacity quantified Missing baryons probed through their absorption Much of the atomic data can be computed, but laboratory benchmarking is invaluable THANK YOU FOR YOUR ATTENTION