Download presentation
Presentation is loading. Please wait.
Published byDominik Milošević Modified over 6 years ago
1
Astronomical Observatory of Rome Arcetri Astrophysical Observatory
X-ray absorption in AGNs Roberto Maiolino Astronomical Observatory of Rome Guido Risaliti Arcetri Astrophysical Observatory
2
Emission components power law FeK cold reflection
3
Warm absorber NH~1022 cm-2 0.2 < D < 20 pc 2-3 components
Kaspi+ 02, Netzer+03, Krongold+ 03 0.2 < D < 20 pc NH~1022 cm-2 2-3 components in pressure eq.
4
Cold absorber
5
Evidence for cold absorption in X-ray spectra
6
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(FeK)
7
NH distribution among AGNs
[OIII] selected Risaliti+ 99 Salvati & Maiolino 01 Distance limited 10-100keV selected Radio selected Markwardt+ 05 Bassani+ 06 Cappi+ 06 Guainazzi+ 06 Sambruna+ 99, Grandi+ 06
8
Heavily obscured AGNs escaping the census
NGC 3690: HII optical spectrum, LX=2x1043 erg s-1, NH=3x1024 cm-2 FeK line Della Ceca+ 02 Ballo+ 04 More cases in local galaxies: optical Sy2 X-ray heavily absorbed Sy2 Maiolino+ 03, Imanishi+ 06,02, Vignati+ 99, Guainazzi+ 00 Also at high-z Comastri+ 02, Severgnini+ 03, Barger+ 05, Cocchia+ 06, Szokoly+ 04
9
X-ray absorption on large scales torii / dust lanes / host disk
400 pc 520 pc ~100pc-scale torii / dust lanes / host disk Compton thin Maiolino & Rieke 95 Malkan+ 98 Matt 00 Guainazzi+ 05
10
X-ray absorption on small scales
Dynamical mass constraints on the size of the Compton thick absorber Circinus, NH= 4x1024 cm-2 torus mass dynamical mass log Mass (M) allowed Risaliti+ 99 R (pc)
11
X-ray absorption on small scales: NH variability
torus BLR torus BLR t ~ years Risaliti+ 06 Elvis+ 05 Puccetti+ 06 t ~ weeks Risaliti+ 02
12
optical and X-ray classification
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 Most extreme cases are BAL QSOs Maiolino+ 01 Gallagher+ 06, Maiolino+ 01, Braito+ 04 Why? Dust-free X-ray absorber Dust properties More cases at high-z Szokoly+ 04, Barger+ 05 Fiore+ 03, Silverman+ 05
13
X-ray absorption versus IR absorption
Silicate 9.7m feature Mid-IR continuum NHSi Shi+ 06 NHX Silva+ 04 Why? Dust-free X-ray absorber Dust properties Mid-IR emission much more extended than X-ray absorber
14
X-ray absorption in high luminosity QSO (QSO2’s)
Extistence questioned until a few years ago. Difficult to find because absorbed and rare. Large numbers of QSO2’s have now been found by systemic surveys over large sky area: Optical Zakamska+ 03, Ptak+ 06 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 Radio Hardcastle+ 06, Donley+ 05, Grandi+ 06, Risaliti+ 03, Vink+ 06 IRAS z=0.44 LX = 2x1046 erg s-1 NH > 5x1024 cm-2 Franceschini+ 00
15
These AGN2’s are mostly Compton thin
Fraction of absorbed AGN versus luminosity AGN2/AGN1 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) Tozzi+ 06 These AGN2’s are mostly Compton thin observed NH distr. in CDFS sensitivity corrected Theoretically explained with “receiding turus” or BH dynamical effects Lamastra+ 06, Wada & Norman 04
16
Inferred from X-ray background
Fraction of Compton thick AGNs at high-z Inferred from X-ray background Compton thick AGNs from Spitzer surveys Polletta+ 06 Alonso-Herrero+06 X-ray undetected IR QSO X-ray detected AGN2 thin AGN1 C-thick/C-thin ~ 2 local ratio Gilli+ 06 required by XRB
17
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) ?
18
AGNs with nuclear H2O maser disks are NOT preferentially Compton thick
Open issues AGNs with nuclear H2O maser disks are NOT preferentially Compton thick Zhang+ 06 log NH (cm-2) NH > cm-2 disk inclination < 10 required for maser amplification
19
X-ray obscuration (< pc) correlated
Open issues X-ray obscuration (< pc) correlated with bars in the host galaxy (> kpc) STRONGLY-BARRED WEAKLY-BARRED NON-BARRED adapted from Cappi+ 06 & Guainazzi+ 05 Maiolino+ 99
20
THE END
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.