testing the agn unified model using spectropolarimetry
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Testing the AGN unified model using spectropolarimetry
Cristina Ramos Almeida Andrés Asensio Ramos, María Jesús Martínez González, Rafael Manso Sáinz,
José Antonio Acosta Pulido & the CanariCam AGN team “Los Piratas”
• Torus dust grains absorb optical & UV photons from matter accretion re-emission in the infrared (peaking at mid-IR 5-30 μm).
• Dust distributed in clumps instead of homogeneously filling torus volume (Nenkova et al. 2002; Hönig et al. 2006; Schartmann et al. 2008).
Modeling
Clumpy Torus ModelsN
enko
va e
t al. (
20
02
)
16th October - Polarization & AGN Cristina Ramos Almeida
• IR range (mid-IR) key to constrain parameters of torus models.
• Goal: isolation of torus emission (Ro< 10 pc; interferometry & mid-IR).
• Large aperture data (e.g. ISO, Spitzer, IRAS) contaminated with circunnuclear stellar emission.
• High-spatial resolution infrared observations (e.g., CanariCam, T-ReCS, Michelle, VISIR) key to isolate torus emission.
Observations
Isolation of Torus emission
16th October - Polarization & AGN Cristina Ramos Almeida
Observations
Isolation of Torus emission
16th October - Polarization & AGN Cristina Ramos Almeida
85 cm Spitzer
8 m Gemini
Mid-IR imaging: space (Spitzer/IRAC) vs. ground (Gemini/T-ReCS) observations
Díaz-Santos (2009, PhD)
• Ground-based subarcsecond resolution mid-IR imaging data for 21 nearby Seyfert galaxies.
• Compilation of near-IR nuclear fluxes from the literature of similar resolutions as mid-IR data.
• Herschel far-IR data also available (GT + GO programmes).
AGN-dominated SEDs = torus emission (Sy2) & torus+AGN emission (Sy1).
16th October - Polarization & AGN Cristina Ramos Almeida
RA et al. 2009, 2011; Alonso-Herrero et al. 2011
Observations
NIR + MIR spectral energy distributions
Results
16th October - Polarization & AGN Cristina Ramos Almeida
• Bayesian code to fit the clumpy models of Nenkova et al. 2008a,b.
• PCA decomposition + Neural networks to approximate Clumpy Database (6 parameters-based models).
• Solution to the Clumpy Database degeneracy • Possibility of interpolating within the database • Simultaneous fit of both SED + spectrum • Prediction of next observation to add to SED • Available for the astrophysical community
Asensio Ramos & Ramos Almeida 2009, 2012
SED modelling
BayesClumpy
16th October - Polarization & AGN Cristina Ramos Almeida
16th October - Polarization & AGN Cristina Ramos Almeida
Circinus
16th October - Polarization & AGN Cristina Ramos Almeida
MIR data from T-ReCS /Gemini-South (Packham et al. 2005; RA et al. 2011)
NIR data from NACO / VLT (Prieto et al. 2010)
NGC 7469
Are the obscuring tori of Type 1 and 2 Seyferts different?
Results
16th October - Polarization & AGN Cristina Ramos Almeida
NIR+MIR emission reproduced with small tori (Ro< 6 pc)
Sy1 tori covering factors < Sy2 tori covering factors
Sy1 Sy1
Sy2 Sy2
Sy1 photon escape prob. > Sy2 photon escape prob.
Results
16th October - Polarization & AGN Cristina Ramos Almeida
Are the obscuring tori of Type 1 and 2 Seyferts different?
Results
16th October - Polarization & AGN Cristina Ramos Almeida
Lawrence & Elvis (2010)
-Highly inclined Seyfert 1 tori:
• Bi-conical outflows (SINFONI; Müller-Sanchez et al. 2011)• Accretion disk orientation from X-ray data (Nandra et al. 2007)
-Expected from warped disk torus models (Lawrence & Elvis 2010)
-also from X-ray observations of Seyfert galaxies (Ricci et al. 2011)
Are the obscuring tori of Type 1 and 2 Seyferts different?
If all Seyfert nuclei are identical, as simple unification predicts, only the viewing angle determines the classification.
Our results suggest that the classification as Type-1 or Type-2 may also depend on the intrinsic properties of the torus.
Results
16th October - Polarization & AGN Cristina Ramos Almeida
Schartmann et al. (2008)
Are the obscuring tori of Type 1 and 2 Seyferts different?
• Origin of unification scheme for Seyfert galaxies (Antonucci & Miller 1985) detection of polarized broad lines in NGC 1068 nuclei.
• Only 30-50% of nearby Sy2s show a Sy1-type polarized spectrum (Tran 2001). Implications?
– 1) not all Seyferts harbour a hidden BLR (Tran 2001, 2003; Gu & Huang 2002)
– 2) distribution of dust within the torus and its inclination not as simple as predicted by the unified model.
Project
16th October - Polarization & AGN Cristina Ramos Almeida
Are the obscuring tori of Type 1 and 2 Seyferts different?
Results from our modelling with torus models could explain lack of polarized broad lines in 50-70% of nearby Seyfert 2 galaxies.
The torus has to have a determined orientation (close to edge-on) and enough clumps to make the broad lines visible in polarized light.
GALAXY NGC 7582 IC 5063
POLARIZED
BROAD LINES ✗✔
i FROM
MODELLING 43°±19°22° 81°±5°
8°
Project
16th October - Polarization & AGN Cristina Ramos Almeida
Are the obscuring tori of Type 1 and 2 Seyferts different?
Results from our modelling with torus models could explain lack of polarized broad lines in 50-70% of nearby Seyfert 2 galaxies.
The torus has to have a determined orientation (close to edge-on) and enough clumps to make the broad lines visible in polarized light.
NGC 7582 ✗ IC 5063 ✔
POLARIZED
BROAD LINES ✔ ✗
i FROM
MODELLING 81°±5°8° 43°±19°
22°
Project
16th October - Polarization & AGN Cristina Ramos Almeida
Are the obscuring tori of Type 1 and 2 Seyferts different?
Results from our modelling with torus models could explain lack of polarized broad lines in 50-70% of nearby Seyfert 2 galaxies.
The torus has to have a determined orientation (close to edge-on) and enough clumps to make the broad lines visible in polarized light.
Comparison between RA11+AH11 results and a homogeneous data set of spectropolarimetric data.
Project
16th October - Polarization & AGN Cristina Ramos Almeida
Are the obscuring tori of Type 1 and 2 Seyferts different?
• Homogeneous dataset of polarized optical spectra of a representative sample of Seyfert galaxies for which we have constraints on their torus properties.
• ISIS/WHT observations scheduled in Jan 2013 16 objects.
• FORS2/VLT observations requested in 2013A 18 objects.
• Sample contains similar numbers of Seyfert 1, 1.2, 1.5, 1.9 and 2 types study how polarization signal varies between types.
Futre observations
16th October - Polarization & AGN Cristina Ramos Almeida
Are the obscuring tori of Type 1 and 2 Seyferts different?
1. Analize in a consistent way linear polarization signal and high angular resolution infrared data using torus models.
2. Confirm whether or not the lack of polarized broad lines in 50-70% of Sy2 population due to low torus inclinations and/or small covering factors.
3. Directly compare between linear polarization signal in Sy1s and Sy2s.
Futre observations
16th October - Polarization & AGN Cristina Ramos Almeida
GOALS
Thanks!
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