a constant pressure model for the warm absorber in ngc 3783
DESCRIPTION
A constant pressure model for the Warm Absorber in NGC 3783. Anabela C. Gonçalves 1 , 3 S. Collin 1 , A.-M. Dumont 1 , A. Rozanska 2 , M. Mouchet 1 , L. Chevallier 1 , R. Goosmann 1 1 Observatoire de Paris-Meudon (LUTH), France 2 Copernicus Astronomical Center (CAMK), Poland - PowerPoint PPT PresentationTRANSCRIPT
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A constant pressure model for the Warm Absorber in NGC 3783
Anabela C. Gonçalves1,3
S. Collin1, A.-M. Dumont1, A. Rozanska2, M. Mouchet1, L. Chevallier1, R. Goosmann1
1 Observatoire de Paris-Meudon (LUTH), France2 Copernicus Astronomical Center (CAMK), Poland3 Centro de Astronomia e Astrofísica da Universidade de Lisboa (CAAUL), Portugal
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Outline
The Warm Absorber (WA) ■ Generic properties
The TITAN code (A.-M. Dumont & S. Collin , Paris Observatory)■ Main characteristics■ Application range and examples
NGC 3783■ The data ■ Previous studies on the WA ■ Preliminary results obtained with the TITAN code
Conclusions and future work
Workshop: some open questions
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The Warm Absorber in AGN
WA general properties
■ WA seems to be located between the disk and the NLR
■ Outflow of material at a few hundreds kms-1, possible multiple velocity components
■ The mass outflow can be important
(exact location? geometry?)
■ Warm (T ~ 105-106 K) plasma surrounding the active nucleus
■ Photoionized by X-rays produced near the black hole
(how much?) Inspired by Fabian (1998)
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Geo
rge et al.
(1995)
NGC 3783
After Chandra and XMM-Newton:
■ Space observatories with grating spectrometers allow for line-resolved spectroscopy
Kasp
i et al. (2002)
Warm Absorber observations
The importance of high(er) spectral resolution
Before Chandra and XMM-Newton (1999):
■ First WA observation in MR 2251-178 by Einstein (Halpern 1984)
Photoionization codes must follow improvement in data quality!
■ ASCA observations show the presence of a WA in ~ 50% nearby Type 1 AGN: detection of absorption edges, no details
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TITAN photoionization code
missing species!
■ Designed for optically thick media (Dumont et al. 2000, Collin et al. 2004)
■ Computes the gas structure in thermal and ionization equilibrium, both locally and globally
■ 102 ions and atoms: H, He, C, N, O, Ne, Mg, Si, S, F
■ Computes the transfer for ~1000 lines and the continuum
■ Modes: Constant Density, Gaseous Pressure or Total Pressure
■ Calculates multi-angle spectra (outward, reflected and transmitted)
■ Accounts for Compton heating/cooling (coupled with NOAR code)
105 < nH < 1014 cm-3
NH < 1026 cm-2
8000 < T < 107 K
10 < < 105
■ Parameters’ optimal range:
= L/nHR2
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Multi-angle spectra■ “normal direction” + 5 cones
(7’, 18°, 40°, 60°, 77°, 87°)
■ computes the transmitted, reflected and outward flux
Computes the transfer of lines and continuum■ No escape probability approximation, but throughout calculations (ALI)
TITAN photoionization code
Line profile studies
■ Accounts for P Cyg-like profiles
● Chandra data
TITAN model
OVIII 18.97
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TITAN application examplesGoosmann et al.
(Poster at “The X-ray Universe 2005”)
Tomorrow: don’t miss Loic’s talk on “The puzzle of the soft X-ray excess in AGN: absorption or reflection? ” !!!
Chevallier et al.
(Poster at “The X-ray Universe 2005”)
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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
■ X-ray (Chandra, XMM) and UV spectra (HST, FUSE): variability studies, line identifications, UV absorption lines studies, …
■ High quality Chandra spectrum, 900 ks exposure (Kaspi et al. 2002)
Kaspi et al. (2002)
=> Stratification of the WA
■ >100 absorption lines detected, covering a wide range in ionization
Krongold et al. (2003)
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Previous NGC 3783 studies
Chandra data (56ks, 900ks spectra) ■ Kaspi et al. (00, 01, 02), Krongold et al. (03), Netzer et al. (03), …
XMM-Newton data (40ks, 280 ks spectra)■ Blustin et al. (2002), Behar et al. (2003), …
Main Results (also discussed in previous talk) ■ 2-phase gas (cold Low-Ionization Phase and hot High-Ionization Phase)
■ absorbing and emitting plasma are manifestations of the same gas
■ 2 or more velocity systems identified in Chandra observations
■ 1 single velocity system in XMM observations (v ~ -600 – -800 km s -1)
■ velocity systems compatible with UV absorption components
■ Albeit extensively studied, WA usually modelled with multiple zones of constant density
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Previous NGC 3783 studies
Netzer et al. (03) modelling
= L/nHR2
NH = 2.1022 cm-2 = 4265 erg cm s-1
NH = 1.1022 = 1071
NH = 8.1021 = 68
■ Simulates the WA stratification with 3 components at constant density:
Netzer et al. (2003)
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 states
■ Using the photoionization code TITAN allows to calculate the temperature, density and ionization structures, plus the absorption and emission spectra
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■ Temperature profile is the same for different densities
■ Radiation pressure is similar, and so is the absorption spectrum, but not the emission component
Pressure equilibrium studies
Comparison to A. Rozanska’s work
■ We use the same code (TITAN), in a more recent version
■ We use the same mode: Total Pressure equilibrium
■ We use a different incident spectrum (not a simple power law spectrum)■ Multi-angle capability available in
most recent versions of the code
■ We can use “real” normal incidence, instead of isotropic approximation
■ We can obtain the emission and absorption contribution separately
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Warm Absorber in NGC 3783
The observations
■ Data taken from the Chandra archives
■ HETG spectra reduced with CIAO 3.2.1
■ Available 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 4x4 models
grid parameters: = 2000, 2500, 3000, 3500 erg cm s-1
NH = 3.1022, 4.1022, 5.1022, 6.1022 cm-2
other parameters: nH (at surface) = 105 cm-3, vturb = 150 kms-1
■ For all models, we have calculated the outward and reflection spectra in multiple directions, plus the ionization and temperature structures
Kaspi et al. (2001)
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Constant density modelConstant Density vs. Total Pressure
Preliminary results
Temperature profiles
■ The WA stratification can be obtained through constant pressure modelsConstant total pressure model
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Preliminary results
Ionization structures
■ The WA stratification can be obtained through constant pressure modelsConstant density model Constant total pressure model
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Preliminary results
Other Pysical quantities
■ e.g. Temperature profile, densityConstant density model Constant total pressure model
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Preliminary results
Warm Absorber size
■ The cloud size is ~ 1.7 x larger for Constant Density models
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Preliminary results
Calculated spectra
■ Our grid can account for the observations
■ The best model (NH = 4.1022 , = 2500) reproduces well the continuum and lines
■ Absorption features blueshifted (~800 kms-1)
Si XIII
Mg XII
Si XIV
Si XIII
Si XIV
S XV
OV
II 7
39eV
OV
III
871e
V
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Conclusions and future workSome 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
■ For this model, we estimated a WA size R ~ 2 1017 cm (0.25 ly or 0.07 pc) compared to a 1.7 x larger WA for a model calculated at constant density
■ For a WA located at R ~ 4 105 RG (bottom NLR) <=>
●●
Mout /MEdd ~ 1(0.72 – 0.79 pc and R/R ~ 0.1)
■ For a WA located at R ~ 4 104 RG (BLR) <=> ●●
Mout /MEdd ~ 0.1(0.07 – 0.15 pc and R/R ~ 1)
■ To be compared to other mass outflows (Blustin PhD Thesis ; Blustin et al. 05): ●●
Mout /Macc < 400, 25 and 6.4 (3 outflowing components) ; 4.3 (average)
■ And WA location: 0.17 pc – 1.8 pc or 2.9 pc (Blustin PhD Thesis; Blustin et al. 05)
R < 5.7 pc (from variability considerations, Krongold et al. 05)
R < 3.2 pc, 0.63 pc and 0.18 pc (3 components, Netzer et al. 03)
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If fcov ~1 => diffuse outward spectra
If fcov <1 => additional reflection spectra If Pcyg-like profiles =>
absorption profile (blueshifted)
outward emission (narrower)
emission from reflection (no shift or redshifted)
Conclusions and future work
Work in progress on the NGC 3673 Warm Absorber
■ Complete the grid with models using different vturb and nH
■ Study the line-emission components to better constrain the covering factor
Future work■ To use TITAN to model the WA observed in other Type 1 and Type 2 AGN
■ Lines missing in the model => complete the TITAN atomic data
■ A larger grid of models aimed at the future use of the code by the community
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Workshop: open questions
How to produce redshifted (or more blueshifted) emission?■ Through balance of different components, line-of-sight projections, and adequate covering factor implying a reflected component
■ Can a “failed wind” explain larger absorption, less blueshifted, and/or redshifted emission?
What kind of geometry does such a model suggest?■ R/R smaller for higher mass output rate, but always within “reasonable” values
■ We can have full covering factor of the source in the line-of-sight and still contribution from the reflection on the neighbouring clouds
■ Cloud size => clumpiness? Preferred geometry?