X-ray Photoionized Models of Emission Spectra Tim Kallman NASA/GSFC. Why Models Emission vs. absorpeon An example ImplicaEons for lab astro

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1 X-ray Photoionized Models of Emission Spectra Tim Kallman NASA/GSFC Why Models Emission vs. absorpeon An example ImplicaEons for lab astro

2 Many astrophysical objects exhibit line emission associated with source of ionizing conenuum If: opecally thin low density Then: Line emission (EW) is proporeonal to intereseng physical quaneees: temperature, ion fraceons lab astro plays key role: f values, collision strengths This procedure has history in opecal/uv Osterbrock and Ferland 2006

3 Can this same procedure be applied to X-ray observaeons? Example: aceve galacec nuclei 1990s à low energy absorpeon ParEal ionizaeon allows leakage of photons below ~0.5 kev SpeculaEon that it should be accompanied by emission o Energy (kev) Reynolds 1997 Netzer 1993

4 2000s: Chandra and XMM Revealed absorpeon lines ~narrow compared with detector From pareally ionized abundant elements: N, O, Si, S, Fe Width~blueshia~1000 km/s No obvious emission Best example: 800 ksec Chandra HETG ObservaEon of NGC3783 Also seen in galacec sources: low mass X-ray binaries (Kaspi et al 2002)

5 Current codes/models can get very good fits warm absorber spectra Full collisional-radiaeve models, all elements Z 30, all ions+neutral atoms, ~10 4 levels, ~10 5 lines, + spectrum synthesis No geometry, dynamics, radiaeve transfer Several codes can do this (cloudy, spex, xstar..) Require at > 2 disenct components in ionizaeon parameter Can get χ 2 /ν~

6 Study of X-ray warm absorbers has become an industry Oumlow, mass loss rate can be large compared with accreeon Seen in ~half of X-ray AGNs, type 1 objects Many publicaeons analyzing these spectra Has been suggested as important for feedback enables black hole to influence host galaxy

7 Corresponding Emission is found in type 2 AGN Lines correspond with lines seen in absorpeon in type 1 objects. Best example: 600 ksec Chandra HETG observaeon of NGC1068 Implies non-spherical distribueon of oumlow And obscuraeon

8 InterpretaEon of absorpeon spectra is affected by saturaeon + limited spectral resolueon Confidence regions for fit of a voigt profile to Si 13+ Lα in the NGC3783 spectrum shows column density uncertainty is ~3x Dominated by systemaecs due to limited spectral resolueon This is (sell) the best s/n line, spectrum log(column/10^22) vturb (km/s)

9 Emission line errors are typically dominated by staesecs Confidence regions for fit of a voigt emission profile to Si 13+ Lα in NGC1068 spectrum column density uncertainty is less than for absorpeon Dominated by staesecs Parameter: norm Confidence contours: C Statistic cross = ; Levels = Parameter: Gamma (kev) tkallman 6 Apr 2018

10 Another example: Si K lines from the high mass binary Vela X-1 High resolution X-ray spectroscopy with XMM-Newton and Chandra, MSSL, October 2002 Sako et al 2002 TABLE 1 Summary of Vela X-1 Observations 7 Vol. 651 Watanabe et al High Mass X-ray Binary = OB star + compact object (neutron star) Orbital separaeon = 1.5 * Rstar à deep X-ray eclipse Compact object accretes from strong stellar wind and emits 422 WATANABE ET AL. X-ray conenuum X-ray conenuum heats, ionizes and is reprocessed by the wind In this system, large range in In this paper we present a quantitative analysis of the X-ray spectra of Vela X-1 first presented by Goldstein et al. (2004) ionizaeonusing the data obtained with the Chandra High Energy Transmis- Figure 9. The forest of Si K lines observed in the spectrum of Vela X-1. Kα lines from at least 8 charge states are detected in this narrow wavelength range. Exposure Label ObsID Start Date Orbital Phase (s) 1 solved with the Chandra HEG. Finally, since most the order of σ < 400 km s. These are again a of the line photons observed during φ = 0.5 come few times smaller than the terminal wind velocity, Feb 05 05:29: Y ,570 from a cylindrical region along the line of cenand are also smaller than those seen, for example, Feb 07 09:57: Y ,430 ters, the magnitude of the observed velocity shifts in a younger O4f star ζ Pup (Kahn et al. 2001; Eclipse Feb 11 21:20: Y ,150 should have been larger than that at φ = 0.0, becassinelli et al. 2001). cause the wind material in this cylinder is movmiller et al. (2002) also report evidences ing right towards the observer at φ = 0.5. In against a simple spherically-symmetric wind other words, the observed projected velocity of through absorption line measurements in Cyg Xv 200 km s 1 is probably close to the true 1. Using several orbital-phase resolved spectra of wind velocity of this material. One possibility the source obtained with Chandra, they were able is that X-ray photoionization inhibits UV drivto qualitatively infer the mass distribution in the ing of the wind and reduces the terminal velocity, system that led them to conclude that the wind sion Grating Spectrometer (HETGS) during three orbital phase in which concase the wind is accelerated only up a is focused along the line of centers, most likely ranges. We construct a simulator to compute the physical certain velocity and coasts at a constant velocity through gravitational attraction by the compact ditions of the surrounding gas for a given binary configuration, (Hatchett & McCray 1977). Another possibility object.

11 Vela X-1 Si lines fit to sum of photoionized emission models Free parameter: ξ=4πf/n, ionizaeon parameter Emission mechanism: fluorescence following K shell photoionizaeon resonance scasering Best fit requires mixture cf. He-like lines, G~1 Geometry is not simple normalized counts s 1 Hz Scasering+fluorescence Wavelength (Å)

12 Emission measure distribueon from fit to Vela X-1 Si K lines Result is approximate power law in ionizaeon parameter Simple prediceon: spherical wind Fit falls below simple prediceon Likely reflects the effect of the X- ray source on the wind dynamics PredicEon for spherical wind Blondin et al

13 Laboratory Astrophysics is needed Line IDs à <0.1% needed Fluorescence yields: ~10% good enough But watch out: Auger damping, channel completeness Future: density, temperature diagnosecs fluorescence yield ion stage Add natalie fig Hell et al. 2016

14 What XARM may detect Si K region Fe K region data and folded model data and folded model normalized counts s 1 Hz Wavelength (Å) tkallman 9 Apr :39 normalized counts s 1 Hz Wavelength (Å) tkallman 9 Apr :52

15 Photoionized X-ray Spectra Challenges Geometry and radieon transfer is important Resonance scasering vs. recombinaeon and fluorescence Complicates the tradieonal strategy of astrophysical diagnosecs AbsorpEon spectra have key systemaec limitaeons DiagnosEc poteneal lies in weak lines There are sell many laboratory astrophysics challenges Accurate wavelengths/energy levels are huge Inner shell processes/fluorescence yields need benchmarking Need to have rate coefficients for temperatures away from equilibrium