Dielectronic recombinationand stability of warm gas in AGN            Susmita Chakravorty     Harvard University, Harvard-...
What is an Active Galactic Nuclei : Its properties Small Angular size                       Sun’s Diameter ~ 1.392 X 106 ...
What is an Active Galactic Nuclei : Its properties               Broad Band Continuum
Broad Band ContinuumRadio      far-IR   optical   EUV   X-ray
Broad Band Continuum
in Radio                                                               Emission lines                                     ...
in Radio                                                               Emission lines                                     ...
in Radio                                                               Emission lines                                     ...
100 pc                 0.1 pc                                 Type II Seyfert Galaxy         Type I Seyfert Galaxy      Ty...
100 pc                 0.1 pc                                 Type II Seyfert Galaxy         Type I Seyfert Galaxy      Ty...
Broad Band ContinuumRadio      far-IR   optical   EUV   X-ray
Signatures of warm absorber Absorption Edges in Soft X-ray Spectra    CV         CVI    OVII     OVIII FeXVII   NeX    39...
Properties of the warm absorber• Partially ionized gas in our line of sight to AGN• Absorption features are blue shifted r...
Why do we care?• Mass loss rate is a substantial fraction of the accretion rate, or     exceeds it.• The X-ray warm absorb...
Stability Curve
Stability Curve                        = L/nR2                    /T ~ (prad)ion/pT                  Curve – phase diagr...
CLOUDY                      http://www.nublado/org/     Inputs  Radiation Field    GeometryNeutral Composition      Densit...
CLOUDY                        http://www.nublado/org/     Inputs                                  Process                 ...
CLOUDY                        http://www.nublado/org/     Inputs  Radiation Field    Geometry                           Te...
Stability Curve           Each point in the curve have thermal             and ionic composition information              ...
Stability CurveImportant Heating and Cooling Processes
Stability CurveImportant Heating and Cooling Processes                WA             WA           WA
Stability Curve       Important Heating and Cooling Processes          Bremsstrahlung          Compton Cooling            ...
Dielectronic recombinationand stability of warm gas in AGN              Susmita Chakravorty et. al,               2008 MNR...
Dielectronic recombination          and stability of warm gas in AGN                          Susmita Chakravorty et. al, ...
Cause : Heating and Cooling agents                                   He+1                            Si+10, Si+11, Si+12  ...
Cause : Column Densities
Cause : Column Densities                                     He+1                                 Si+10, Si+11            ...
Dielectronic recombination     (the most likely candidate?)          Quantum mechanical calculations          Experiment...
Dielectronic recombination     (the most likely candidate?)          Quantum mechanical calculations          Experiment...
Future directions         Extensive quantitative study looking for        other possible causes.         Check the relia...
Dielectronic recombination and stability of warm gas in AGN
Dielectronic recombination and stability of warm gas in AGN
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Dielectronic recombination and stability of warm gas in AGN

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Paper presented by Susmita Chakravorty at the 17th International Conference on Atomic Processes in Plasmas, Queen's University Belfast, 19-22 July 2011.

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Dielectronic recombination and stability of warm gas in AGN

  1. 1. Dielectronic recombinationand stability of warm gas in AGN Susmita Chakravorty Harvard University, Harvard-Smithsonian CfA Ajit Kembhavi Martin Elvis Gary Ferland N. R. Badnell 2008 MNRAS, 384L, 24 The 17th International Conference on Atomic Processes in Plasmas Queen’s University, Belfast 22nd July 2011
  2. 2. What is an Active Galactic Nuclei : Its properties Small Angular size Sun’s Diameter ~ 1.392 X 106 km AGN ~ Size of a star Highly luminous (≥galactic) Milky Way ~ 1044 ergs/sec AGN ~ 1042 – 1048 ergs/sec
  3. 3. What is an Active Galactic Nuclei : Its properties Broad Band Continuum
  4. 4. Broad Band ContinuumRadio far-IR optical EUV X-ray
  5. 5. Broad Band Continuum
  6. 6. in Radio Emission lines in Optical Edge on Radio Galaxy Infrared Type II Seyfert Galaxy Type II QuasarUV and X-rays Gamma Rays Type I Seyfert Galaxy (Inverse Compton) Type I Quasar BL Lac Object
  7. 7. in Radio Emission lines in Optical Edge on Radio Galaxy Infrared Type II Seyfert Galaxy Type II QuasarUV and X-rays Gamma Rays Type I Seyfert Galaxy (Inverse Compton) Type I Quasar BL Lac Object
  8. 8. in Radio Emission lines in Optical Edge on Radio Galaxy Infrared Type II Seyfert Galaxy Type II QuasarUV and X-rays Gamma Rays Type I Seyfert Galaxy (Inverse Compton) Type I Quasar BL Lac Object
  9. 9. 100 pc 0.1 pc Type II Seyfert Galaxy Type I Seyfert Galaxy Type II Quasar Type I Quasar
  10. 10. 100 pc 0.1 pc Type II Seyfert Galaxy Type I Seyfert Galaxy Type II Quasar Type I Quasar
  11. 11. Broad Band ContinuumRadio far-IR optical EUV X-ray
  12. 12. Signatures of warm absorber Absorption Edges in Soft X-ray Spectra CV CVI OVII OVIII FeXVII NeX 392 490 740 870 1260 1360 (eV)C (V & VI) O (V - VIII) Fe (XVII - XXII) Ne (IX & X) Mg (XI & XII) Si (XIII - XVI)  (eV)
  13. 13. Properties of the warm absorber• Partially ionized gas in our line of sight to AGN• Absorption features are blue shifted relative to opticalemission lines, indicating outflow• Column Density (NH) ~ 1022±1 cm-2• Ionization Parameter  ~ 10 – 1000 erg cm s-1• Temperature ~ 105 K – 106.5 K = L/nR2• Density (nH) ~ 109 cm-3 (105 - 1012) /T ~ (prad)ion/p• Distance from the source ~ 0.01 – 100 pc
  14. 14. Why do we care?• Mass loss rate is a substantial fraction of the accretion rate, or exceeds it.• The X-ray warm absorber could coexists with a UV absorber.• Distance from the source ~ 0.01 – 100 pcWe need to understand warm absorber nature• Is the Warm Absorber in thermodynamic equilibrium?• If so, does the gas have multiphase nature?
  15. 15. Stability Curve
  16. 16. Stability Curve = L/nR2 /T ~ (prad)ion/pT Curve – phase diagram P
  17. 17. CLOUDY http://www.nublado/org/ Inputs Radiation Field GeometryNeutral Composition Density Thickness
  18. 18. CLOUDY http://www.nublado/org/ Inputs Process Basic Assumption Radiation Field Atomic processes reached time-steady state Geometry n(X i )(X i )  n(X i  1 )neG (X i 1, T)Neutral Composition Thermal balance achieved  Coll   IC  (Ph  C ) / n Density Working principle Thickness ni     njRji  Source  ni   Rij  Sink   0  ji  t ji  
  19. 19. CLOUDY http://www.nublado/org/ Inputs Radiation Field Geometry TeqNeutral Composition Density Thickness Output  Thermal state & Ionic composition of cloud
  20. 20. Stability Curve Each point in the curve have thermal and ionic composition information Stable = L/nR2 /T ~ (prad)ion/p Unstable Curve – phase diagram High temperature low density 2-Phase phase mediumStable Low temperature high density phase
  21. 21. Stability CurveImportant Heating and Cooling Processes
  22. 22. Stability CurveImportant Heating and Cooling Processes WA WA WA
  23. 23. Stability Curve Important Heating and Cooling Processes Bremsstrahlung Compton Cooling Compton Heating WAPhotoionization Cooling by recombination of metals Bremsstrahlung WA WA
  24. 24. Dielectronic recombinationand stability of warm gas in AGN Susmita Chakravorty et. al, 2008 MNRAS, 384L, 24 C84 1993 to 1996 (Reynolds – Fabian, ‘95) & C07, 2007
  25. 25. Dielectronic recombination and stability of warm gas in AGN Susmita Chakravorty et. al, 2008 MNRAS, 384L, 24 C84 1993 to 1996 (Reynolds – Fabian, ‘95) & C07, 2007Version 5 Nphases log(/T) Mlog(/T) ~105K ~106K C84 45 2 0.05 0.47 0.05 C07 74 2 0.22 0.46 0.07
  26. 26. Cause : Heating and Cooling agents He+1 Si+10, Si+11, Si+12 Fe+21, Fe+22, Fe+23 O+6, O+7 Fe+17 to Fe+25
  27. 27. Cause : Column Densities
  28. 28. Cause : Column Densities He+1 Si+10, Si+11 All of Fe, but Fe+21, Fe+22, Fe+23It’s the cooling agents which make a difference
  29. 29. Dielectronic recombination (the most likely candidate?)  Quantum mechanical calculations  Experimental estimates  Revisited by Badnell and coworkers (2000 - 2007)  Rates are substantially larger for quite a few ions.  The cooling agents are among the species analysed.  The differences in stability curves are due to these changes.  It is therefore necessary to revisit older calculations.
  30. 30. Dielectronic recombination (the most likely candidate?)  Quantum mechanical calculations  Experimental estimates  Revisited by Badnell and coworkers (2000 - 2007)  Rates are substantially larger for quite a few ions. Savin et.al. 1999, ApJS, 123, 687  The cooling agents are among the species analysed.  The differences in stability curves are due to these changes.  It is therefore necessary to revisit older calculations.
  31. 31. Future directions  Extensive quantitative study looking for other possible causes.  Check the reliability at lower temperatures – still a very active domain of update in atomic data base.

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