3. The Sample
Why should we study AGN?
Motivation
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
What kind of physical processes drive
the phenomena near SMBH?
What can we learn from the
Corona of an AGN?
9. The SampleCompton scattering
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
● Photon - Electron collision
● When photons lose energy, it is
“Recoil Effect”
● For low energy interactions, the
scattering follows Thompson
cross-section σT
10. The SampleCompton scattering
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Wavelength change
Thompson
cross-section
Normalized energy;
Electron radius
11. The SampleCompton Scattering, Total cross-section
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Klein-Nishina formula
● For low energy interactions (x<<1)
● For high energy interactions (γ>>1)
12. The SampleCompton Scattering, Total cross-section
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[Longair2011]
13. The SampleInverse Compton Scattering (ICS)
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● Photon - Electron collision
● Photons gain energy
● Cooling mechanism for hot
electron cloud
Net energy gain
14. The SampleSpectrum of ICS
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Ertley2014
15. The SampleComptonization
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
If Inverse Compton Scattering is the dominant
process in a medium, then the process is called
Comptonization
17. The SampleComptonization
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
In the low energy
regime:
For symmetrical Thompson
scattering
Photon Energy
Loss/Electron
energy gain
18. The SampleComptonization
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Hence...
● 4kT >> hν: Energy transfer from electrons to
photons
● 4kT = hν: Equilibrium
● 4kT << hν: Energy transfer from photons to
electrons (recoil effect)
19. The SampleComptonization
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Finally... Optical depth
Comptonization
Parameter
Number scattering
Mean free path
[Rybicki & Lightman 1986]
20. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
● Low energy photons upscattered in hot plasma cloud
● The plasma cloud is thermal
● The hard X-ray tail (spectral shape) is formed by photons that
have undergone
● The shape of the hard radiation spectrum does not depend on
the low frequency photon source distribution
21. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Photons described by
occupation number function
Diffusion in Energy and
Configuration Space
Energy space
function can be
derived by solving
the Comptonization
Stationary Equation
(CSE)
Spatial function
describes the
escape rate
Independent diffusion
22. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Outcome…
● An asymptotic power law in soft
energies
● A hard X-ray tail:
○ Wien tail in the non-relativistic
case
○ Modified Wien tail in the
relativistic case
23. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
The computational interpretation of this model in XSPEC is:
compTT (5 parameters)
Other componization models are:
● compPS (19 parameters) [Poutanen & Svensson 1996]
● Nthcomp (5 parameters) [ Zdziarski, Johnson & Magdziarz 1996]
26. The SampleOutline
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
● Study Seyfert I galaxies
● Swift/BAT 70-month all sky survey
● Spectral fitting using a Comptonization model
● Seek potential correlation between the corona and
○ SMBH Mass
○ Soft X-ray luminosity 2-10 keV
○ Eddington ratio λEDD
● Look for a physical mechanism that can explain the results
27. The SampleOur sample (1)
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
67 sources
● Seyfert I type
● NuSTAR observations
● Known redshifts
● Available black hole mass
28. The SampleOur sample (2)
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Why NuSTAR?
● Excellent spectra quality
● An order of magnitude
greater than BAT
● Unprecedented hard X-ray
quality
Specifications
● 10 meter focusing
telescope (1st > 10 keV)
● Two identical censors
(FPMA, FPMB)
● Operation energy band 3-
79 keV
● Energy resolution
○ 0.4 at 6 keV
○ 0.9 at 60 keV
29. The SampleOur sample (3)
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Why not Swift/BAT data?
Low quality; An order
of magnitude
difference
Not contemporary
observations; Variability
effects; Cross-calibration
problems
31. The SampleBlack hole mass
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Velocity Dispersion
(Kormendy and Ho,
2013)
FWHM of Ha and Hβ
emission lines
(Trakhtenbrot and
Netzer, 2012;
Greene and Ho, 2005)
BAT AGN Spectroscopic Survey (BASS)
(see Koss et al 2017; Ricci et al 2017)
AGN Mass catalog
By Bentz and Katz, 2015
http://www.astro.gsu.edu
/AGNmass/
03
01 02
Sources flagged as
“Excellent” and “Accepted”
have been used
32. The SampleRedshift and Mass Histogram
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33. The SampleSpectral modeling
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
(Arnaud,1996)
Wabs compTT Pexrav Gaussian
Par 1 NH (1022 # cm-2) Redshift z (fixed) Γ photon index E line (keV)
Par 2 Input photons (keV) Ec = 3 kt (keV) E width (keV)
Par 3 Plasma Temp. (keV) Rel refl (fixed -1)
Par 4 Optical depth Abund >He
Par 5 Geometry (fixed 2) Abund Fe
Par 6 Redshift z (fixed)
In XSPEC notation: WA*COMPTT+PEX+GA
Normalization
[Morrison & McCammon (1983); Titarchuk (1994); Magdziarz & Zdiarski (1995)]
34. The SamplePlasma Temperature and Optical Depth Histogram
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
35. The Sample
Having parsed kt and τ...
Extra properties...
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Eddington
Luminosity
Eddington
ratio
[Vasudevan & Fabian 2009]
36. The Sample
Median values of our results...
Results
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
37. The Sample
In order to check whether
the pairs of kT and τ have
physical meaning, we draw
the photon index line in the
τ-kT plane
The photon index Γ...
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
[Petrucci et al 2001]
38. The SampleThe Optical Depth, Plasma Temperature plane
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
39. The SampleAny correlation..?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Plasma
Temperature
Optical Depth
SMBH Mass
Soft X-ray luminosity
2-10 keV
Eddington
Ratio λEDD
40. The SamplePlasma Temp. and Optical Depth vs Black Hole Mass
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Tortosaetal2018
41. The SamplePlasma Temp. and Optical Depth vs Black Hole Mass
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Tortosa et al 2018
Ricci et al 2018
42. The SamplePlasma Temp. and Optical Depth vs Black Hole Mass
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Tortosa et al 2018
Ricci et al 2018
43. The SamplePlasma Temp. and Optical Depth vs Black Hole Mass
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
44. The SampleAny correlation..?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Plasma
Temperature
Optical Depth
SMBH Mass
Soft X-ray luminosity
2-10 keV
Eddington
Ratio λEDD
45. The SamplePlasma Temp. and Optical Depth vs L 2-10 keV
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
46. The SampleAny correlation..?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Plasma
Temperature
Optical Depth
SMBH Mass
Soft X-ray luminosity
2-10 keV
Eddington
Ratio λEDD
47. The SamplePlasma Temp. and Optical Depth vs λEDD
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Tortosaetal2018
48. The SamplePlasma Temp. and Optical Depth vs λEDD
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Ricci et al 2018
49. The SamplePlasma Temp. and Optical Depth vs λEDD
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Ricci et al 2018
50. The SamplePlasma Temp. and Optical Depth vs λEDD
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
51. The SampleAny correlation..?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Plasma
Temperature
Optical Depth
SMBH Mass
Soft X-ray luminosity
2-10 keV
Eddington
Ratio λEDD
52. The SampleIs there any physical “Thermostat” ?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
The Θ-l plane
Dimensionless
Temperature Θ
Compactness l
[Ricci et al 2018]
[e.g. Fabian et al. (2009); Chartas et al. (2009)]
53. The SampleIs there any physical “Thermostat” ?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
The Θ-l plane
Dimensionless
Temperature Θ
Compactness l
[Ricci et al
2018]
[e.g. Fabian et al. (2009);
Chartas et al. (2009)]
Pair production in the Θ-l plane
Svensson (1984) describes a thermal plasma
cloud in pair balance, where the pair
production region in the Θ-l plane is given by
54. The SampleIs there any physical “Thermostat” ?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Kamrajetal2018
55. The SampleIs there any physical “Thermostat” ?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Ricci et al 2018
56. The SampleIs there any physical “Thermostat” ?
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
57. The SampleTake home message...
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
● Comptonization model works well on coronae
● No correlation between the corona and the AGN has been
found
● Pair production mechanism is likely to regulate the coronal
conditions; “Thermostat”
● Non-thermal states may allow sort “visits” in the pair
production region [Fabian+15;Fabian+17}
● Future deeper observations will (probably) fill the cool and
low luminosity region
58. The SampleTake home message...
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
● Comptonization model works well on coronae
● No correlation between the corona and the AGN has been
found
● Pair production mechanism is likely to regulate the coronal
conditions; “Thermostat”
● Non-thermal states may allow sort “visits” in the pair
production region
● Future deeper observations will (probably) fill the cool and
low luminosity region
60. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Photons are being diffused in
both the energy and
configuration space
61. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Solution...
u corresponds to the number
of scatterings
62. The SampleGeneralized Comptonization [Titarchuk 1994]
Giorgos Dimopoulos | master thesis | g.dimopoulos@noa.gr
Solution...
u corresponds to the number
of scatterings