AGN disk emission through X-ray and UV absorbers - iucaa

AGN disk emissionthrough X-ray and UV absorbersSusmita ChakravortyHarvard University, Harvard-Smithsonian CfAJulia LeeHarvard University, Harvard-Smithsonian CfA16 January 2011 Wide Band X-ray astronomy 1

Background‣ Warm Absorber signatures – 0.3 to 2 keV‣ X-ray spectral components of the AGN SED• The 1-10 keV powerlaw• The soft excess at ~500 eVSoft ExcessAccretion diskcomponentPower-lawWAAnother significant componentAGN disk at ~ 10 ev16 January 2011 Wide Band X-ray astronomy 2

Plan of talk‣ Can we decipher the exact shape of the accretion disk spectrum?• Use multi-wavelength data for AGN.• Can we derive physical parameters like M BH and m?‣ Use the UV to X-ray ionizing continuum• Does it affect the warm absorber?• What are its effect on the UV absorber?• Can we draw conclusions on the stability properties of thewarm absorber?• Possible implications for the metallicity of the absorber16 January 2011 Wide Band X-ray astronomy 3

Constraining M BH and m for AGN16 January 2011 Wide Band X-ray astronomy 4

Multi-wavelength SED for AGN• Red filled squares areobserved data points.• Near simultaneous X-ray andOptical data.SpitzerCompositeQSO• Infrared from Spitzer,2MASS and IRAS.IRAS2MASSHETChandra• Green filled squares are`average SED for AGN’ in UV(Telfer et.al. 2002).• The blue lines are arbitrary,simplistic joins between EUVand X-ray.16 January 2011 Wide Band X-ray astronomy 5

Multi-wavelength SED for AGN• Red filled squares areobserved data points.• Near simultaneous X-ray andOptical data.SpitzerCompositeQSO• Infrared from Spitzer,2MASS and IRAS.IRAS2MASSHETChandra• Green filled squares are`average SED for AGN’ in UV(Telfer et.al. 2002).• The blue lines are arbitrary,simplistic joins between EUVand X-ray.• We wish to model the far UVpart of the SED with “diskbb”.16 January 2011 Wide Band X-ray astronomy 6

Disk Emission in terms of M BH and m‣ Disk model - iso-temperature annuli of accreted matter;each annulus radiating as a blackbody (Shakura & Sunyaev 1973)‣ Diskbb in Xspec or Isis (Makishima et.al. 1986)‣ The temperature profileR.has dependance on M BH and mAccretion diskcomponent‣ T in = T(R in ) is an input in the“diskbb” model, where R in is radiusof innermost stable annulusSoft ExcessPower-law‣ The normalisationhas dependence on M BH through R inand is an input in the “diskbb” model.7

Ionizing continuum‣ Accretion disk component by“diskbb”Accretion diskcomponent‣ Soft Excess• Compton reflection of disk photons byplasma at 100 eV, modeled by “nthcomp.Soft ExcessPower-law• Blackbody at 100 eV - X-ray photonsreflected off the disk.‣ Powerlaw‣ Siemiginowska et.al. 1995‣ Vasudevan & Fabian 200916 January 2011 Wide Band X-ray astronomy 8

Disk Emission in terms of M BH and mR16 January 2011 Wide Band X-ray astronomy9

Disk Emission in terms of M BH and m16 January 2011 Wide Band X-ray astronomy 10

Disk Emission in terms of M BH and m16 January 2011 Wide Band X-ray astronomy 11

Disk Emission in terms of M BH and m16 January 2011 Wide Band X-ray astronomy 12

Ionizing continua16 January 2011 Wide Band X-ray astronomy 13

Ionizing effect of disk on warm absorber16 January 2011 Wide Band X-ray astronomy 14

Warm AbsorberSignatures‣ Absorption features in the Soft X-ray SpectraCV CVI OVII OVIII NeIX NeX MgXI MgXII SiXIII SiXIVC (V & VI) O (V - VIII) Fe (XVII - XXII) Ne (IX & X) Mg (XI & XII)Al (XII & XIII) Si (XIII - XVI) S (XV & XVI)‣ Absorption features are blue shifted relative to optical emissionlines, indicating outflow.‣ N H ~ 10 22±1 cm -216 January 2011 Wide Band X-ray astronomy 15

Derived propertiesWarm Absorber‣ Partially ionized gas in our line of sight to AGN‣ = L/nR 2 ~ 10 – 1000 erg cm s -1‣ T gas ~ 10 4 K – 10 6.5 K‣ n H ~ 10 9 cm -3 (10 5 - 10 12 )-- Ionization parameter-- Temperature of the gas-- Density of the gas‣ R gas ~ 0.01 – 100 pc-- Distance of the gas from the central engine‣ Mass loss rate is a substantial fraction of the accretion rate, orexceeds it.(Mathur et.al. 1995, 1998, Crenshaw et.al. 1999)‣ The X-ray warm absorber could coexists with a UV absorberLy NV SiIV CIV16

Effect of accretion disk on the warm absorber• The high ionization species of X-ray absorberremain unaffected by the presence of UV photons.• However, OVII ion fraction under estimated by30% without UV part of SED.• For reasonable ion fractions of the UV ions, theaccretion disk component is necessary.• Demonstrates the need to know the SED in theultraviolet for a complete description of theabsorbing ions.

On the thermodynamic stabilityof the warm absorberTP

On the thermodynamic stabilityof the warm absorberNo diskDisk

Multiple phases in pressure equilibriumDiskZ sol9Z sol16 January 2011 Wide Band X-ray astronomy20

Summary• Careful reconstruction of the accretion disk component can give valuableconstraints on the mass and accretion rate of the black hole at the centre ofthe AGN.• Astrosat may be very helpful in this area in future.• The accretion disk has significant effect on warm absorber, especially ionswith IP ≤ 740 eV (OVII).• The UV - X-ray absorber connection is better explained if the diskcomponent is included in the analysis.• Warm absorber becomes thermodynamically more stable with the inclusion ofthe disk component• but multiple phases at different temperatures are not in pressureequilibrium• need super-Solar warm absorber for multi-phase.16 January 2011 Wide Band X-ray astronomy 21