Observations and modelling of ionized gas in Active Galactic Nuclei Anabela C. Gonçalves Paris Observatory (LUTH), Lisbon Astronomical Observatory (CAAUL)

Observations and modelling of ionized gas in Active Galactic Nuclei

Anabela C. Gonçalves

Paris Observatory (LUTH), Lisbon Astronomical Observatory (CAAUL)

S. Collin, A.-M. Dumont, M. Mouchet (Paris Observatory, France),

A. Rozanska, L. Chevallier (CAMK, Poland), R. Goosmann (Astronomical Institute, Czech Rep.)

A new model for the Warm Absorber in NGC 3783

Outline

Active Galactic Nuclei (AGN)

■ Standard model

■ Optical ionized gas: Broad Line Region (BLR), Narrow Line Region (NLR)

■ X-ray ionized gas: Warm Absorber (WA)

Future work and perspectives

The Warm Absorber

■ General Properties

■ The Warm Absorber in NGC 3783

■ The data and the models

■ Results obtained with the TITAN code (Gonçalves et al., A&AL, in press)

■ Conclusions

Standard and Unifying models

Standard Model

■ Transformation of gravitational energy into radiation

■ Supermassive black hole

■ Accretion disk

■ Obscuring torus

■ Ionized gas

■ Visible spectra: BLR, NLR

■ X-ray spectra: WA

BLR

NLR

WA gas

© Urry & Padovani

The Warm Absorber

General WA properties

■ Warm (T ~ 105-106 K) plasma surrounding the active nucleus

■ Photo-ionized by UV/X-rays produced near the black hole

■ WA seems to be located between the BLR and the NLR (same location as Coronal Lines)

■ Outflow of material at a few hundreds kms-1, often multiple velocity components

■ The mass outflow can be important (how much?)

Warm Absorber Observations

■ The importance of higher spectral resolution

Before Chandra and XMM-Newton (1999):

■ Einstein observations of MR 2251-178 suggest a variable column density of material photo-ionized by the active nucleus (Halpern 1984)

■ Photo-ionization codes must follow improvement in data quality!

■ ASCA observations show the presence of WA in ~ 50% nearby Type 1 AGN: detection of absorption edges, no details

Geo

rge et al.

(1995)

After 1999:

■ Space observatories with grating spectrometers allow for line-resolved spectroscopy: physics of the WA gas

Kasp

i et al. (2002)

Warm Absorber in NGC 3783

NGC 3783

■ Seyfert 1.5 at z = 0.0097, V ~ 13.5 mag, also very bright in X-rays and UV

■ One of the strongest X-ray warm absorbers known

■ Spectra available in the X-rays and UV: variability studies, absorption lines

■ High quality Chandra spectrum, 900 ks exposure (Kaspi et al. 2002)

■ Albeit extensively studied, usually modelled with multi-zones of constant density

■ >100 absorption lines detected, wide range in ionization => stratification of the WA

Kaspi et al. (2002)


Previous data fitting and models

■ Needed multiple regions at constant density to simulate the WA stratification

Kaspi et al. (2000, 2001, 2002):

■ gaussian fit of the lines, spline interpolation of the continuum

= L/nHR2

NH = 2.1022 cm-2 = 4265 erg cm s-1

NH = 1.1022 = 1071

NH = 8.1021 = 68

Netzer et al. (2003):

■ 3 components at constant density:

Netzer et al. (2003)

The TITAN code (Dumont et al. 2000, Collin et al. 2004)

■ computes the transfer for ~1000 lines and the continuum (ALI method)

■ models media at constant density or gas/total pressure

■ computes the temperature, density and ionization structures

■ knowledge of the multi-angle flux, providing the outward (absorption, emission) and reflected spectra


Our approach: a single medium in Total Pressure equilibrium

■ Results in the natural stratification of the WA

■ Allows to explain the presence of lines from different ionization levels

■ Can be modelled with TITAN


The observations

■ Data taken from the Chandra archives (900 ks, Kaspi et al. 2002)

■ Multi-wavelength observations provide information on incident spectrum

The Model

■ Incident spectrum as in Kaspi et al. (2001): broken power-law continuum

■ We have built an optimized grid of models to study NGC 3783

variable parameters: 2000 < < 3500 erg cm s-1 (ionization par)

3.1022 < NH < 6.1022 cm-2 (coldens)

fixed parameters: nH = 105 cm-3 (density), vturb = 150 kms-1

■ For all models, we have calculated the outward spectra in multiple directions, plus the ionization and temperature structures

Results with the TITAN code

Temperature structures

■ The WA temperature stratification can be obtained through constant total pressure models

Constant total pressure modelConstant density model


Ionization structures

■ The WA stratification can be obtained through constant pressure models, which are able to justify the presence of lines covering a wide range in ionization

Constant density model Constant total pressure model


Ionic column densities

■ Comparison between our single-zone model and Netzer et al.’s composite model gives similar results

■ TITAN code also provides information on the lower-ionization species responsible for the UV lines


Outward spectra

■ Our optimized grid of models can account for the observations

■ A model with NH = 4.1022 and = 2500 reproduces well the continuum and available lines

■ Absorption features are blueshifted by ~ 800 kms-1 (outflow velocity)

Si XIII

Mg XII

Si XIV

Si XIII

Si XIV

S XV

General conclusions

■ The TITAN code is well adapted to the study of the WA in AGN

■ The WA in NGC 3783 can be modelled under total pressure equilibrium

■ Our best model has nH = 105 cm-3, NH = 4 1022 cm-2, = 2500 erg cm s-1

■ Based on our best model results, on the object’s bolometric luminosity (L~2.1044 erg s-1) and BH mass (MBH~3.107 M), we estimate the

WA size to be R ~ 4 1017 cm (0.13 pc) (to be compared to a 1.7x larger WA for a constant density model)

■ In order to keep Mout /MEdd <~ 1 the WA is, at the furthest, at a

distance R ~ 1018 cm (0.32 pc, i.e. before the NLR)

● ●

Conclusions on the WA

■ To be compared to the published values of 0.18 < R < 3.2 pc (Netzer et al. 03)

■ R < 5.7 pc (from variability, Krongold et al. 05)

Future work on ionised regions

■ Model the WA observed in other type 1 and type 2 AGN (NGC 1068, NGC 5548)

collaboration with O. Godet (Leicester U., UK) and the TITAN team (Observatoire de Paris, France, and CAMK, Poland)

■ Better constrain the physical properties of the WA gas (ne => R) through the

multi-wavelength (IR, Optical) study of Coronal Lines

collaboration with M. Ward (Durham U., UK)

■ UV and Optical studies of AGN winds

collaboration with Nahum Arav (Colorado U., US)

■ The Study of Ultra-Luminous X-ray sources

collaboration with R. Soria (Harvard Smithsonian, US)

■ Measure the BH masses and accretion rates in AGN, through BLR studies

collaboration with S. Collin (Paris Observatory, France), B. Peterson (Penn State U., US), M. Vestergaard (Stewart Observatory, US), T. Kawaguchi (NAOJ, Japan)

Grid of constant Ptot models

■ Parameters covered by the test grids: ionization parameter 1000 < < 4000 incident continuum (a power-law) slope: 1.1 < < 2.3

ionised medium column density: 1022 < NH < 1023

■ These models can be applied to a variety of astronomical objects

■ They can be used to simulate observations (useful for next generation satellites)

■ Grid of models converted into FITS table models usable by XSPEC, and thus by a larger astrophysical community

■ They will integrate the models database (Portail Numérique de l’Obs. de Paris)

■ Computed with TITAN (abs, emi, ref)

■ Benchmark: 3 grids of 45 models each (to be extended soon: Titanic, IDRIS)

■ Resolution et Energy range compatible with XMM-Newton

Perspectives

Observations and modelling of ionized gas in Active Galactic Nuclei

S. Collin, A.-M. Dumont, M. Mouchet (Paris Observatory, France),

A. Rozanska, L. Chevallier (CAMK, Poland), R. Goosmann (Astronomical Institute, Czech Rep.)

Anabela C. Gonçalves

Paris Observatory (LUTH), Lisbon Astronomical Observatory (CAAUL)

N. Arav, (Colorado U., US), T. Contini (Midi-Pyrénées Observatory, France),

O. Godet (Leicester U., UK), T. Kawaguchi (NAOJ, Japan), B. Peterson (Penn State U., US),

R. Soria (Harvard Smithsonian, US), P. Véron, M.-P. Véron-Cetty (OHP, France),

M. Vestergaard (Steward Observatory, US), M. Ward (Durham U., UK) ...

Ionized regions in AGN

■ ionization mechanisms, through diagnostic diagrams

■ gas kinematics and geometry, through line-widths and line-profiles

■ abundances, temperature, and density, trough specific line-ratiosNLR

Warm Absorber (WA)■ outflows (can influence growth of BH and host galaxy), trough X-ray and UV studies

■ density nH (not well constrained), from lines (coronal, He-like) and variability

■ distance R (not well constrained), from the density and ionization parameter

■ ξ=L/nHR2 from photo-ionization modelling, L from spectrum => only nH*R2 is known!

■ thickness R, from nH and NH

■ abundances, temperature T and ionization structures from photo-ionization models

■ Pressure P, from nH and T

■ Mass outflow rate Mout, from nH and outflow velocity (blueshifted lines)

●

■ distances, through reverberation mapping, thus BH masses

■ gas kinematics and geometry, through line-widths and line-profilesBLR

Emission line regions

The Narrow Line Region (NLR)

■ more extended region

■ larger distances (106-108 Rg)

■ lower densities (nH ~ 103-106 cm-3)

■ column density: 1020 - 1022 cm-2

■ coverage factor < 0.01

■ line widths ~ hundreds of kms-1

The Broad Line Region (BLR)

■ compact region (< 1 pc)

■ close to central engine (103-104 Rg)

■ high densities (nH ~ 109 - 1012 cm-3)


■ coverage factor > 0.1

■ line widths ~ thousands of kms-1

■ distances through reverberation mapping, thus BH masses

■ structure and kinematics through line-widths and line-profiles

■ structure and kinematics through line-widths and line-profiles

■ abundances, temperature, density, through specific line-ratios

■ ionization mechanisms, through diagnostic diagrams

Emission line regions

The Narrow Line Region (NLR)

■ more extended region

■ larger distances (101066-10-108 8 RgRg)

■ lower densities (Ne ~ 103-106 cm-3)


■ coverage factor < 0.01 coverage factor < 0.01

■ very small filling factorvery small filling factor

■ line widths ~ hundreds kms-1

■ conic structure conic structure

The Broad Line Region (BLR)

■ compact region (< 1 pc)

■ close to central engine (103-105 Rg)

■ high densities (Ne ~ 109 - 1012 cm-3)


■ coverage factor > 0.1

■ line widths ~ thousands kms-1

■ photoionized medium with ionization parameter =L/nR2 1

Emission-Line Galaxies

Type 1 AGN

Type 2 AGN

BL Lacs

Liners

Narrow Line Seyfert 1 galaxies

Main optical characteristics■ Noticed by Osterbrock & Pogge (1985)

■ FWHM (H) < 2000 kms -1

■ [O III]5007/H < 3

■ Strong Fe II emission often present

■ Large FeII/HFeII/H and small [OIII]/H and small [OIII]/H

Interesting X-ray properties■ Rapid, high-amplitude variability

■ Steep X-ray spectra and high slope diversity

■ Soft X-ray excess

(Pogge 2000)

■ ~ 15% of type 1 AGN up to z = 0.5

Creation of the X-rays

Hotter and diluted medium emitting hard X-rays

The existence of two media is required:

~109 K 105 – 106 K

Colder and denser medium emitting soft X-rays

Irradiation, heating bydirect Compton scattering

Cooling by inverse Compton effects

X-ray production in AG

AGN spectra and X-ray emission

X-ray spectrum

■ Arises in the inner regions of the central engine

■ A hotter (109 K) diluted medium emits the hard X-rays

■ A colder (105-106 K) denser medium emits the soft X-rays

Hard X-ray band

■ Fe K line, relativistic disk profile

■ Reflection component

Soft X-ray band (~0.1-2 keV)

■ Soft excess

■ Strong absorption edges

■ Highly ionized absorption and/or emission lines

■ Absorption features blueshifted by several hundreds kms-1

Documents

Observations and modelling of ionized gas in Active Galactic Nuclei Anabela C. Gonçalves Paris Observatory (LUTH), Lisbon Astronomical Observatory (CAAUL)