New Suzaku Results on Active Galaxies or Reflections on AGN James Reeves (Keele) and Suzaku team (given by Lance Miller)
Overview Overview of Suzaku and instrument performance. Why Suzaku is important for AGN studies Description of Observations. Focus on hard X-ray science for AGN, especially absorption/reflection study Discussion - how common are broad/relativistic emission lines? What can we learn about inner regions of AGN? - how does the iron line and Compton reflection hump vary? - what is the role of absorption? Are there disk winds? - how does the Unified model for AGN fit in with current observations?
Suzaku launched in July 2005. Provides broad-band X-ray spectroscopy from 0.3-200 kev
The Scientific Payload on Suzaku Instruments 4XRT & XIS (X-ray CCD): 3 front side (FI) CCD and 1 back side (BI) CCD. Energy range 0.2-12 kev X-ray Telescope HXD (Well-type phoswich counter): PIN (10-80 kev) and GSO (50-600 kev) active shields as GRB monitor (WAM=Wide-band Allsky Monitor). high signal to noise from 0.3 to 200 kev Hard X-ray Detector ~1000 cm2 effective area in 1-6 kev band (XIS) extremely low background (XIS, HXD) excellent spectral resolution, especially at E<1 kev improved line spread function on low energy side (XIS) Both of these are important properties for AGN research. X-ray Imaging And very powerful for extended sources. Spectrometer
Hard X-ray Sensitivity is key for AGN studies. Below 10 kev Suzaku has similar effective area to XMM-Newton (but better spectral resolution). Hard X- ray detector has lower background than Beppo-SAX over most of bandpass. Swift BAT catalog has ~250 AGN above the flux level limit (1 mcrab) of the HXD/PIN Hard X-ray background in Suzaku, vs RXTE and Beppo-SAX (Mitsuda et al. 07) BAT high latitude Log N-Log S (Markwardt et al 2006, Tueller et al. 2008)
Anatomy of an Active Galactic Nucleus X-ray absorption (ionized gas) (Kallman et al 2004) Urry & Padovani (1995) X-ray Reflection (Guilbert & Rees, Lightman & White 1988, George & Fabian 1991, Ross & Fabian 2005)
XMM/Chandra Suzaku Absorption from outflow Iron K Line Suzaku s Broad Bandpass X-ray Continuum Soft Excess Compton Reflection hump
Example - Suzaku Observation of Circinus (Seyfert 2 galaxy). Courtesy T Yaqoob
Suzaku XIS: Excellent Soft X-ray Spectral Resolution Observation of Compton-thick Seyfert 2 Markarian 3 (Awaki et al. 2008) Soft X-ray emission lines Broad-band model O/Ne/Mg/Si/S Fe direct reflection
Suzaku Measurement of Iron Line Profile and Reflection in MCG -5-23-16 (Reeves et al. 2007) XIS FI HXD/ PIN HXD/ GSO Iron line profile deconvolved into broad and narrow components. Reflection hump measured with accuracy (R=1.2±0.2, A Fe =0.5±0.1) Iron K line profile Broad-band Suzaku observation allows us to deconstruct the absorption, reflection and iron line emission from the intrinsic continuum.
Broad-band Suzaku observations can be interpreted as relativistic line/disk reflection in MCG -6-30-15 (Miniutti et al. 2007) Warm Absorber Iron K Line Reflection Hump Jan 06, 300ks exposure Ratio Strong Reflection (R>2)?
Can Suzaku Infer the Spin of Black Holes? MCG 5-23-16 (no evidence for black hole spin) MCG 6-30-15 (spinning black hole?)
Variability of Iron line and Reflection in MCG-6-30-15 (Miniutti et al. 2007) Suzaku lightcurve No variations in Fe line/reflection - gravitational light bending around a BH? If reflection at ~3 kev, emission must be from ~2 r g implying a Kerr BH (Miniutti & Fabian 2004) Constant Reflection hump and iron line
PCA deconstruction of MCG -6-30-15 with Suzaku (Miller, Turner & Reeves 2008) Eigenvector 1 - variable compt constant offset compt Power-law * warm absorption only No variable Fe line Constant Fe line / reflection and/or partialcovering absorption Ratio to Γ=2.2 Ratio to Γ=2.2
Why Does the Broad Iron line and Reflection Component not appear to vary - (i) Gravitational Light Bending? Might observationally confirm that space-time very close to the black hole is "warped", a key component in Einstein's General Relatively Light paths close to the black hole can be sharply curved: photons traveling away from the accretion disk can be redirected onto the disk When the X_ray source is closest to the BH, the photons are bent towards the disk and a stronger reflection spectrum is seen.
Not relativistic light-bending but absorption in MCG -6-30-15? (Miller et al. 2008) mean spectrum Partial covering absorption CXB absorbed reflection Model consists of:- intrinsically variable power-law (with ionized absorber). Partially covered absorbed power-law, high column 10 23 cm -2 distant absorbed reflection or more high-column absorption Good fit to full set of timevariable spectra in broad-band Suzaku/XMM datasets. Reproduces absorption lines in Chandra/HETG, XMM/RGS grating observations
A Compton-thick Absorber in the Type 1 QSO, 1H 0419-577 (Turner et al. 2009 submitted) Type 1 QSO, 1H 0419-577 at z=0.104. High L/L Edd AGN. With absorption Without absorption strong hard excess in HXD. Cannot be explained by reprocessed (reflected) emission. Needs Compton-thick (N H ~10 24 cm -2 ) absorption subtending ~10% of the sky at the source Located close to black hole (likely within/about optical BLR) Very asymmetric CIV - signature of a thick disk wind?
Relativistic Outflow in PDS 456 (Deep Suzaku Observation, 190ks, Feb 07) High luminosity QSO z=0.184 L BOL ~10 47 erg s -1 Pair of blue-shifted absorption lines observed with Suzaku at 9.08/9.66 kev (systemic rest frame) or 7.68/8.15 kev (observed). NOT associated with obvious transition at z=0 frame, ruling out WHIM or local bubble. Outflow velocity of 0.26/0.32c, if associated with Fe XXVI 1s-2p (6.97 kev) In PDS 456, outflow rate is ~25M solar /yr assuming only 10% covering. At 1/3c, the KP of outflow is 10 47 ergs -1, similar to bolometric output.
Geometries for AGN inner regions? Reflection dominated Absorption dominated Light Bending (GR) Inhomogeneous disk Outflow
10 9 Outflows can regulate growth of black holes Outflows expected from high Eddington-rate accretors (eg King & Pounds 2003) Direct correlation between the bulge/galaxy mass and black hole mass (i.e. M-Sigma relation). Massive black holes grow by accretion. Powerful outflows can provide the feedback for this process, by shutting off the supply of material to the BH. Black hole mass 10 3 Stellar system mass 10 6 10 12
(Braito et al. in prep) A different view of Seyfert 2s? Suzaku XIS + HXD PIN (Ueda et al. 2007) Mrk 348 Swift J0138.6-4001 Swift-BAT selected Seyfert 2s, heavily absorbed (N H ~ 10 24 cm -2 ) with high nominal reflection fraction (R~2), very weak scattered emission (< 0.5%), featureless optical spectra. Implies very little photoionized gas - a highly buried AGN but where we can nonetheless see the reflection spectrum.
The Standard Unification Scheme of AGN How well does this hold up with current observations? Type I AGN can have large amount of X-ray obscuring matter on compact (sub pc) scales - e.g. within the torus or BLR and most likely associated with a high column disk wind. Type 2 AGN are highly obscured but not necessarily by a neat torus (e.g. Ueda et al. 2007, Winter et al. 2008)
Conclusions New Suzaku observations are revealing that the AGN accretion flow is less simple than expected in standard thin accretion disk model. Some type I AGN have Compton-thick column densities greater than predicted by unified models. Absorbing gas appears compact (Broad-line region scales). Outflows are a common property of many AGN. Disk-winds observed in Type I AGN. Leads to a picture of a complex absorbing and perhaps reflecting disk wind shaping the broad-line region and dominating the X-ray regime In high luminosity AGN outflows may reach near-relativistic velocities, transmitting a substantial fraction of the energy output - a source of feedback? Not all Type II AGN conform to the standard AGN unified model. Future calorimeter resolution (<6 ev) spectra will provide a wealth of data at Fe K on high column density outflows. Hard X-ray imaging will reveal new types of obscured black holes (e.g. NeXT, Simbol-X, IXO).