Xray absorption in AGNs Roberto Maiolino Astronomical Observatory

X-ray absorption in AGNs Roberto Maiolino Astronomical Observatory of Rome Guido Risaliti Arcetri Astrophysical Observatory

Emission components pow er l a w Fe. K n co ld re tio c fle

Warm absorber Kaspi+ 02, Netzer+03, Krongold+ 03 NH~1022 cm-2 0. 2 < D < 20 pc 2 -3 components in pressure eq.

Cold absorber

Evidence for cold absorption in X-ray spectra

Warnings: • X-ray absorption due to metals assumption on metallicity to convert Nmet NH • A reflection-dominated spectrum may be associated with a “fossil” AGN (not Compton thick) Gilli+ 00, Matt+04, Guainazzi+ 06 FX EW(Fe. K)

NH distribution among AGNs [OIII] selected Risaliti+ 99 Salvati & Maiolino 01 Distance limited 10 -100 ke. V selected� Radio selected� Cappi+ 06 Guainazzi+ 06 Markwardt+ 05 Bassani+ 06 Sambruna+ 99, Grandi+ 06

Heavily obscured AGNs escaping the census NGC 3690: HII optical spectrum, LX=2 x 1043 erg s-1, NH=3 x 1024 cm-2 Fe. K line Della Ceca+ 02 Ballo+ 04 More cases in local galaxies: optical Sy 2 X-ray heavily absorbed Sy 2 Maiolino+ 03, Imanishi+ 06, 02, Vignati+ 99, Guainazzi+ 00 Also at high-z Comastri+ 02, Severgnini+ 03, Barger+ 05, Cocchia+ 06, Szokoly+ 04

X-ray absorption on large scales c 400 p 520 ~100 pc-scale torii / dust lanes / host disk Compton thin Maiolino & Rieke 95 Malkan+ 98 Matt 00 Guainazzi+ 05 pc

X-ray absorption on small scales Dynamical mass constraints on the size of the Compton thick absorber Circinus, NH= 4 x 1024 cm-2 s to ru log Mass (M ) sm as s l a c i s ma am n y d allowed R (pc) Risaliti+ 99

t ~ years torus X-ray absorption on small scales: NH variability BLR Risaliti+ 02 t ~ weeks Risaliti+ 06 Elvis+ 05 Puccetti+ 06

X-ray absorption versus optical absorption AV/NH generally lower than Galactic Mismatch between optical and X-ray classification (type 1) log NH (cm-2) Wilkes+ 02, Hall+ 05 Maiolino+ 01 Why? • Dust-free X-ray absorber • Dust properties Most extreme cases are BAL QSOs Gallagher+ 06, Maiolino+ 01, Braito+ 04 More cases at high-z Szokoly+ 04, Barger+ 05 Fiore+ 03, Silverman+ 05

X-ray absorption versus IR absorption Silicate 9. 7 m feature NHSi Mid-IR continuum Shi+ 06 NHX Silva+ 04 Why? • Dust-free X-ray absorber • Dust properties • Mid-IR emission much more extended than X-ray absorber

X-ray absorption in high luminosity QSO (QSO 2’s) Extistence questioned until a few years ago. Difficult to find because absorbed and rare. Large numbers of QSO 2’s have now been found by systemic surveys over large sky area: Optical Zakamska+ 03, Ptak+ 06 IRAS 0910+41 z=0. 44 X-ray Norman+ 02, Fiore+ 03, Severgnini+ 03, Barger+ 05, Silverman+ 05, Maccacaro+04 Infrared Martinez-Sansigre+ 05, Polletta+ 06, Alonso-Herrero+ 06, Braito+04, Franceschini+ 05 LX = 2 x 1046 erg s-1 NH > 5 x 1024 cm-2 Radio Hardcastle+ 06, Donley+ 05, Grandi+ 06, Risaliti+ 03, Vink+ 06 Franceschini+ 00

Fraction of absorbed AGN versus luminosity AGN 2/AGN 1 decreases with luminosity Hasinger 06, Ueda+ 04, La Franca+ 05, Barger+ 05, Akylas+ 06 X-ray surveys (but see also Dwelly+06, Treister & Urry 05) These AGN 2’s are mostly Compton thin observed NH distr. in CDFS Tozzi+ 06 sensitivity corrected Theoretically explained with “receiding turus” or BH dynamical effects Lamastra+ 06, Wada & Norman 04

Fraction of Compton thick AGNs at high-z Inferred from X-ray background Compton thick AGNs from Spitzer surveys X-ray undetected IR QSO AGN 2 thin Polletta+ 06 AGN 1 C-thick/C-thin ~ 2 local ratio Gilli+ 06 X-ray undetected required by XRB X-ray detected Alonso-Herrero+06

Open issues: Geometry and dynamics - Distance: is a compact (~BLR scale) absorber ubiquitous? - Do every AGN have Compton-thick gas around it ? -Structure: two phase medium (cold, dense clouds inside warm gas), or more homogeneous, cold gas with density gradients ? -Stability: how is the vertical structure supported ? Dynamical stability (inflow, outflow) ?

Open issues AGNs with nuclear H 2 O maser disks are NOT preferentially Compton thick Zhang+ 06 log NH (cm-2) NH > 1023 -24 cm-2 disk inclination < 10 required for maser amplification

Open issues X-ray obscuration (< pc) correlated with bars in the host galaxy (> kpc) STRONGLY-BARRED WEAKLY-BARRED NON-BARRED Maiolino+ 99 adapted from Cappi+ 06 & Guainazzi+ 05

THE END