Models%20of%20Comptonization

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Models of Comptonization
Models of Comptonization
P.O. Petrucci LAOG, Grenoble, France
P.O. Petrucci LAOG, Grenoble, France

• The Comptonization process
• Astrophysical applications
• The advances expected with simbol-X

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The Comptonization Process

• Discovered by A.H. Compton in 1923
• gain/loss of energy of a photon after collision
  with an electron

If electron at rest
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Thermal Comptonization
Hot phase corona

Tc, t
Comptonization on a thermal plasma of electrons
characterized by a temp. T and optical depth t
Cold phase acc. disc

• mean relative energy gain per collision

for E kT
for E ? kT

• mean number of scatterings

? Compton parameter
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Thermal Comptonization Spectrum
(Beloborodov 1999, Malzac et al. 2001)
(Courtesy J. Malzac)
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Geometry dependence
Isotropic geom
Corona
Tc, t
G(Tc, t)
Disc
First scattering order
kTc
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Geometry dependence
kT 100 keV and t 0.5
kT 100 keV and same G
Slab
t 0.5
Sphere
t 1
t 0.7
Cylinder
? geometrical degeneracy
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Radiative Balance
If the 2 phases are in radiative equilibrium, the
corona temperature and optical depth follow, for
a given geometry, a univocal relationship.
(Haardt Maraschi 1991 Stern et al. 1995)
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Non-thermal Comptonizaton

• For electron with large Lorentz factor

? very efficient energy transfert

• Comptonization by a non-thermal distribution of
  electrons

?
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Astrophysical Context
Present in all SIMBOL-X science cases !

• AGNs (Thermal Comp. in Seyfert galaxies,
  non-thermal Comp. in Blazars)

Madgziarz et al. (1998)
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Astrophysical Context
Present in all SIMBOL-X science cases !

• AGNs (Thermal Comp. in Seyfert galaxies,
  non-thermal Comp. in Blazars)

• X-ray binaries (Thermal Comp. in the hard state,
  non-thermal Comp. (?) in the Intermediate and
  Soft states)

Cyg X-1
Hard State
Soft State
Zdziarski et al. (2002)
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Astrophysical Context
Present in all SIMBOL-X science cases !

• AGNs (Thermal Comp. in Seyfert galaxies,
  non-thermal Comp. in Blazars)

• X-ray binaries (Thermal Comp. in the hard state,
  non-thermal Comp. (?) in the Intermediate and
  Soft states)

• X-ray background
• Galaxy clusters
• Supernovae remnants
• GRBs

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Simulation I
NGC 5548, Seyfert galaxy L2-10 keV 10-11
erg.s-1.cm-2 kTe 250 keV, t 0.1 and R 1.
Slab geometry. (Tsoft fixed)
No spectral degeneracy any more with 50 ks
1 ks 5 ks 50 ks
Rem
This can be complicated by complex
reflection/absorption features
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Simulation I
NGC 5548, Seyfert galaxy L2-10 keV 10-11
erg.s-1.cm-2 kTe 250 keV, t 0.1 and R 1.
Slab geometry.
Both geometries agree with the data in the Simbol
X energy range with exposures of 50 ks
Slab
Cylinder
Breaking the geometrical degeneracy will
require long exposure
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Spectral Variability
a few corona crossing time
Coronal flare
coronal flare
initial state
Opt. depth
Corona crossing time
Disc flare
disc flare
Temperature
Corona crossing time
Malzac Jourdain (2000)
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Simulation II
Cyg X-1, microquasar L2-10 keV 10-9
erg.s-1.cm-2 kTe 100 keV, t 1.7 and R 0.3
Texp 500 s
(see Malzacs talk)
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Simulation III
Bright blazars spectra well determined in 1 ks !
Constrains on the Synchrotron Self-Compton
process from multi-? observations (see tomorrows
talks)
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What can we expect with SIMBOL-X?

• Strong constrains on Thermal comptonization model
  (on dynamical time scale for AGNs, on very short
  time scale in XrBs)
• This picture can be complicated by the presence
  of complex absorption/emission features
• The broadest energy range is needed,
  multi-wavelength observations recommended. (CTA,
  GLAST, HERSCHEL, ALMA, LOWFAR, WSO-UV, ...).