Radio quiet AGN

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Radio quiet AGN

• B. Czerny
• Copernicus Astronomical Center Warsaw

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VHE are radio quiet AGN of any interest?

• bad news only a small fraction of energy
  emitted above 100 KeV
• good news AGN are the best probes of GR X-ray
  spectroscopy

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Outline

• general introduction
• X-ray spectroscopy
• current developments
• based on results obtained in collaboration
  with S. Collin
• R. Goosman, M. Mouchet,
• A.-M. Dumont, M. Dovciak,
• V. Karas, A. Rozanska, G. Ponti

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Radio quiet AGN intro

• Definition
• Properties L from 1047 erg/s down
• broad band spectra

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Radio-quiet AGNintro
What are they? Black holes
John Michell (1724-1793)
Roy Kerr (1934-)
Karl Schwarzschild (1873-1916)
Albert Einstein (1879-1955)
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Radio quiet AGN intro

• What are they?
• Accreting black holes

M 106 1010 Ms M from tens of
Ms/year down
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Type 1 and type 2 objects

• Type 1 viewed roughly face on
• not strongly obscured
• but warm absorber present
• Type 2 viewed at high inclinations
• strongly obscured (so
  called dusty/molecular
  torus most probably a
  type of wind)
• High energy processes better followed in type 1
  objects

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Components

• Cold optically thick accretion disk
• Hot optically thin plasma geometry under
  discussion

Paticles roughly in Keplerian motion if pressure
gradient unimportant General relativity effect
presence of the marginally stable orbit
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Emission of accretion disks

• Stationary cold Keplerian acccretion disk

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Accretion disk spectra

• Tmax 105 K
• Disk emission peaks in far UV

Composite spectrum of bright quasars from sample
of Fransis et al. (1991) after Morris, disk black
body fit and schematic representation of the
composite of Zheng et al/Laor et al.
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AGN flow geometry
Plausible geometry
L/LEdd lt 0.1 disk far from marginally stable
orbit L/LEdd 0.1 1 disk approaches marginally
stable orbit L/LEdd gt 1 disk puffs up
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Hot plasma emission

• Bremsstrahlung
• Synchrotron
• Compton scattering
• They form broad band spectra, difficult to
  assign to any particular distance from the
  gravity center problems with definite
  determination of geometry

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Cold plasma emission

• Thermal emission T 105 K
• Reprocessing of incident hard X-rays
• - thermalization
• - Thomson/Compton scattering
• - emission of atomic lines
• In AGN elements like C,N,O, Si, S, and Fe are
  not fully ionized in the disk even close to the
  marginally stable orbit
• The option of line emission gives the full
  advantage of X-ray spectroscopy

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Broad Ka iron line

• The shape of iron line tests the particle motion
  close to horizon

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First detecion of Ka line

• Detection of broad line in MCG -6-15-30 in
  ASCA data (Tanaka et al.. 1995)

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New observations of K?
Broad line in the same object (MCG-6-30-15)
measured with XMM (Fabian et al. 2002)
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Variability of the line profile

• Detection Line profile in of variosu luminosity
  states in ASCA data (Iwasawa et al.. 1996) broad
  line in MCG -6-15-30 in ASCA data (Tanaka et al..
  1995)

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Variability of hard X-rays

• Lightcurve of MCG -6-15-30 form XMM (Ponti et
  al.. 2004)

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Time-dependent process
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Single spot

• Computations of the reflection component require
  solution of radiative transfer
• - continuum
• - hundreds of atomic lines
• A few codes exists. Titan/Noar code of Collin,
  Dumont Abrassart (2000) is the best for
  optically thick media.

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Local spectrum

• Result depends on the flare phase

Local X-ray spectrum of irradiated accretion disk
(Collin et al. 2003) State 2 unexpanded
disk State 3 disk expanded due to the X-ray
heating
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Single spot
R. Goosmann, in preparation
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Spot motion, light propagation in curved space
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Mean and rms spectra
Model parameters a 0.95 , i 30 deg, M 107
Ms Tfl 2e5 (r/18)3/2 s, Ffl r-3 s,
uniform flare distribution Work in progress
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Single flare observations

• Bright flare from MCG -6-15-30

Ponti et al.. 2004
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Iron line delay in a single flare
Ponti et al. 2004
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In which sense AGN are better than GBH ?

• Typical current count rate
• 10 cts/s 10 000 cts/s
• Typical Keplerian timescale at inner disk orbit
• 103 s 10-3 s
• so counts per single orbit
• 100 cts 10 cts
• lower ionization level
• GBH better for evolutionary studies

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Spatial resolution of observations
Typowe osiagane zdolnosci rozdzielcze Typ
Masa Odleglosc 1cm
1RSchw GBH 10 10 kpc
1017 3x1011 Milky Way 2.6x106
10 kpc 1017 106 MBH
107 50 Mpc 5x1020
109 MBH 109 1 Gpc
1022 2x109
Specjalne techniki (VLBI, fotometria plamkowa)
pozwalaja osiagnac wyniki lepsze o pare rzedów
wielkosci, ale to wciaz za malo. Obszar w
bezposredniej bliskosci czarnej dziury mozna
jednak badac posrednio poprzez analize widma
promieniowania, takze w zaleznosci od czasu.
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Are central objects indeed black holes?

• So far everything is consistent with GR
  expectations although accuracy is not high

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If something looks like a black hole
From www page of Peter King
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