A constant pressure model for the Warm Absorber in NGC 3783

1. 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 1Observatoire de Paris-Meudon (LUTH), France 2Copernicus Astronomical Center (CAMK), Poland 3Centro de Astronomia e Astrofísica da Universidade de Lisboa (CAAUL), Portugal

2. 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

3. Inspired by Fabian (1998) The Warm Absorber in AGN WA general properties ■Warm (T ~ 105-106 K) plasma surrounding the active nucleus ■ Photoionized by X-rays produced near the black hole ■ 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?) (how much?)

4. NGC 3783 George et al. (1995) After Chandra and XMM-Newton: ■Space observatories with grating spectrometers allow for line-resolved spectroscopy Kaspi 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 byEinstein (Halpern 1984) ■ASCA observations show the presence of a WA in ~ 50% nearby Type 1 AGN: detection of absorption edges, no details Photoionization codes must follow improvement in data quality!

5. ■Parameters’ optimal range: 8000 < T < 107 K 10 < x < 105 105 < nH < 1014 cm-3 NH < 1026 cm-2 x = L/nHR2 TITAN photoionization code ■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 missing species! ■Computes the transfer for ~1000 lines and the continuum ■ Modes: Constant Density, Gaseous Pressure or Total Pressure ■ Accounts for Compton heating/cooling (coupled with NOAR code) ■ Calculates multi-angle spectra (outward, reflected and transmitted)

6. Multi-angle spectra ■ “normal direction” + 5 cones (7’, 18°, 40°, 60°, 77°, 87°) ■ computes the transmitted, reflected and outward flux OVIII l 18.97 ●Chandra data TITAN model Line profile studies ■ Accounts for P Cyg-like profiles TITAN photoionization code Computes the transfer of lines and continuum ■ No escape probability approximation, but throughout calculations (ALI)

7. TITAN application examples Chevallier et al. (Poster at “The X-ray Universe 2005”) Goosmann 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? ” !!!

8. Krongold et al. (2003) 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) ■>100 absorption lines detected, covering a wide range in ionization => Stratification of the WA Kaspi et al. (2002)

9. 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

10. Netzer et al. (2003) ■Simulates the WA stratification with 3 components at constant density: NH = 2.1022 cm-2x = 4265 erg cm s-1 NH = 1.1022x = 1071 NH = 8.1021x = 68 x = L/nHR2 Previous NGC 3783 studies Netzer et al. (03) modelling 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

11. ■ 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

12. Warm Absorber in NGC 3783 The observations ■ Data taken from the Chandra archives ■ HETG spectrareduced with CIAO 3.2.1 ■Available multi-wavelength observations provide information on incident spectrum Kaspi et al. (2001) 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:x = 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

13. Constant Density vs. Total Pressure Constant density model Preliminary results Temperature profiles ■ The WA stratification can be obtained through constant pressure models Constant total pressure model

14. Preliminary results Ionization structures ■ The WA stratification can be obtained through constant pressure models Constant density model Constant total pressure model

15. Preliminary results Other Pysical quantities ■ e.g. Temperature profile, density Constant density model Constant total pressure model

16. Preliminary results Warm Absorber size ■ The cloud size is ~ 1.7 x larger for Constant Density models

17. OVII 739eV OVIII 871eV Si XIV Si XIV Si XIII Mg XII Si XIII S XV Preliminary results Calculated spectra ■ Our grid can account for the observations ■ The best model (NH = 4.1022 , x = 2500) reproduces well the continuum and lines ■ Absorption features blueshifted (~800 kms-1)

18. ■ To be compared to other mass outflows (Blustin PhD Thesis ; Blustin et al. 05): ● ● ● ● ● ● Mout /MEdd ~ 0.1 Mout /Macc < 400, 25 and 6.4 (3 outflowing components) ; 4.3 (average) Mout /MEdd ~ 1 ■ And WA location: 0.17 pc – 1.8 pc or 2.9 pc (Blustin PhD Thesis; Blustin et al. 05) R < 3.2 pc, 0.63 pc and 0.18 pc (3 components, Netzer et al. 03) R < 5.7 pc (from variability considerations, Krongold et al. 05) Conclusions and future work Some 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 DR ~ 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) <=> (0.72 – 0.79 pc and DR/R ~ 0.1) ■ For a WA located at R ~ 4 104 RG (BLR) <=> (0.07 – 0.15 pc and DR/R ~ 1)

19. 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

20. 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? ■DR/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?