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Studying AGN with high- resolution X-ray spectroscopy Jelle Kaastra SRON Nahum Arav, Ehud Behar, Stefano Bianchi, Josh Bloom, Alex Blustin, Graziella Branduardi-Raymont, Massimo Cappi, Elisa Costantini, Mauro Dadina, Rob Detmers, Jacobo Ebrero, Peter Jonker, Chris Klein, Jerry Kriss, Piotr Lubinski, Julien Malzac, Missagh Mehdipour, Stéphane Paltani, Pierre-Olivier Petrucci, Ciro Pinto, Gabriele Ponti, Eva Ratti, Katrien Steenbrugge, Cor de Vries
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2 Introduction: The influence of AGN outflows Dispersal heavy elements into IGM & ICM Ionisation structure IGM evolution host galaxy How created? Structure? Mass & energy? Confinement? Crucial to understanding central engine: –Accretion process –Energy budget
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3 AGN outflows in a nutshell Photo-ionised gas v = -100 to -1000 km/s Seen through line and continuum absorption Spectrum ionic column densities ionization parameter ξ=L/nr² Kaastra et al. 2000
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4 Photoionisation modelling Radiation impacts a volume (layer) of gas Different interactions of photons with atoms cause ionisation, recombination, heating & cooling In equilibrium, ionisation state of the plasma determined by: –spectral energy distribution incoming radiation –chemical abundances –ionisation parameter ξ=L/nr 2 with L ionising luminosity, n density and r distance from ionising source; ξ essentially ratio photon density / gas density
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Question 1: Structure outflow Is it more like rather uniform density clouds in pressure equilibrium? Or is it more like coronal streamers, with lateral density stratification? 5
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Absorption measure distribution 6 Ionisation parameter ξ Emission measure Column density Discrete components Continuous distribution Temperature
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7 Separate components in pressure equilibrium? Not all components in press. eq. (same Ξ) Division into ξ comps often poorly defined Continuous N H (ξ) distribution? Others fit discrete components What's going on? Steenbrugge et al. 2005
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8 Question 2: Where is the gas? Photo-ionization modeling ξ=L/nr² L obtained from spectrum only the product nr² known, not r or n Is gas accelerating, decelerating?
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Density estimates: line ratios C III has absorption lines near 1175 Å from metastable level Combined with absorption line from ground (977 Å) this yields n n = 3x10 4 cm -3 in NGC 3783 (Gabel et al. 2004) r~1 pc Only applies for some sources, low ξ gas X-rays have similar lines, but sensitive to higher n (e.g. O V, Kaastra et al. 2004); no convincing case yet 9
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10 Density estimates: reverberation If L increases for gas at fixed n and r, then ξ=L/nr² increases change in ionisation balance column density changes transmission changes Gas has finite ionisation/recombination time t r (density dependent as ~1/n) measuring delayed response yields t r n r
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11 Reverberation: NGC 3783 RGS data (Behar et al. 2003): no change in Warm absorber n 10 pc. EPIC data (Reeves et al. 2003): change in Warm absorber (larger columns) n>10 8 cm -3, r<0.02 pc.
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12 Observation campaign Mrk 509 Core: 10 x 60 ks XMM, spaced 4 days (RGS, EPIC & OM all used!) Simultaneous Integral 10 x 120 ks Followed by 180 ks Chandra LETGS, simultaneous with 10 orbits COS (HST) Preceded with Swift (UVOT, XRT) monitoring Supplemented with ground-based (WHT, Pairitel) photometry & grism Period: 4 Sept – 13 Dec 2009 (100 days) 7 papers submitted/accepted, 8 in progress
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General data analysis issues Excellent quality many new steps developed RGS: full usage multi-pointing mode, refinements combining spectra with variable hot pixels, λ-scale, effective area, reducing response 2Gb 8 Mb, rebinning…) See Kaastra et al. 2011; see auxilary programs in SPEX distribution www.sron.nl/spexwww.sron.nl/spex PN: Triggered by our campaign improved gain cal OM: extended wavelength range optical grism HST/COS: extensive efforts to improve data analysis for this high-quality spectrum SPEX: allows simultaneous fitting high-res UV & X-ray spectra 13
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Broad-band spectrum & variability (Mehdipour et al., Petrucci et al., talks this afternoon) 14
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. Broad and neutral Fe K emission well correlated with continuum emission on few days time- scales. No relativistic profile Origin outer disc or inner BLR Fe-K line & variability (Ponti et al.; talk Petrucci et al.) 3-10 keV flux Line Intensity
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16 OM Grism spectrum
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17 UV-optical variability (OM, Swift) Source was in outburst (0.1 dex in UV) right in the middle of ourt campaign!
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ISM absorption (talk Pinto et al. on Monday) 18
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Abundances (Steenbrugge et al., poster G45) 19
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COS & FUSE UV Absorption lines in Mrk 509 (Kriss et al., talk this afternoon) O VI,Lyβ, & Lyγ from FUSE (Kriss et al. 2000) 14 velocity components seen in COS UV spectrum C IV doublet split by only 500 km/s, so grey regions can’t be used for optical-depth Red lines: velocities X-ray absorbers XMM-Newton/RGS Blue lines: velocities X-ray absorbers Chandra/LETGS 20
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LETGS + COS data (Ebrero et al., poster G14) X-rays: outflow with 3 distinct ionization phases in form of multi-velocity wind. UV spectra: absorption system with 13 kinematic components Analysis kinematic properties & column densities absorbers UV-absorbing gas co- located with & embedded in lower density high-ionization X-ray absorbing gas 21
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22 Stacked RGS spectrum Galactic O I edge Several narrow absorption lines Detection 31 individual ions Tight upper limits column densities 18 other ions Two main velocity components (+40 and -300 km/s) Highly ionised ions in general higher velocity
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23 No O I from host galaxy O I host galaxy (not detected, N H <5x10 18 cm -2 )
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24 X-ray analysis in more detail Fit spectra using a power law + modified blackbody (or even a spline) continuum Where needed, add emission lines: BLR or NLR X-ray lines (no relativistic lines needed) Fit warm absorber using a model ionic or total column densities Using photo-ionisation model, derive absorption measure distribution N H (ξ) Spectral fits done with SPEX, global fits
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25 Sample high-resolution spectra
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26 Example of broad emission lines O VIII Lyα O VII triplet
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Photoionisation modelling RGS spectrum (Detmers et al. 2011) Use time-averaged SED Test dependence on SED Proto-solar abundances Multiple ionisation, 3 velocity components Same ion may be present in more than one velocity/ionisation component! 27 Mehdipour et al. 2011
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28 Discrete versus continuous absorption measure distribution? Column densities well approximated by sum of 5 components (see table) Higher column for higher ionisation parameter But what about a continuous model? AB C D E
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29 Continuous model Fitted columns with continuous (spline) model Surprise: comps C & D pop-up as discrete components! Upper limits FWHM 35 & 80 % Component B (& A) too poor statistics to prove if continuous Component E also poorer determined: correlation ξ and N H. C D B E
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Where is the gas? Needs t-dependent model For each of the 5 components: if L increases, ξ must increase (as ξ=L/nr 2 ) From 10 continuum model fits predicted ξ change for each of 10 observations, compared to average spectrum If gas responds immediately, transmission outflow changes immediately 30
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31 Expected response absorbers for 0.1 dex luminosity increase
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Time-dependent photo- ionisation Time evolution ion concentrations n i : dn i /dt = A ij (t) n j A ij (t) contains t- dependent ionisation & recombination rates 32
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Location photoionised gas (work in progress) Component A: Rotating, low ionisation disk + high velocity outflow, 3 kpc (direct imaging [O III] 5007, Philips 1986) Component C: >10 pc (lack of response) Component E: > 1 pc? (lack of response?) See also Kriss (talk this afternoon) and poster Ebrero 33
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34 Mass loss through the wind v (km/s)-100-1000 ξ=1ξ=10.0010.0001 ξ=10001.00.1
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35 Conclusions Deep, multi-wavelength monitoring campaigns (AGN) are rewarding: High quality spectra, not limited by statistics “Continuous” light curves, allowing to monitor the variations
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