Testing the AGN unified model using spectropolarimetry Cristina Ramos Almeida Andrés Asensio Ramos,...

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

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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


Observations

Isolation of Torus emission


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).


RA et al. 2009, 2011; Alonso-Herrero et al. 2011

Observations

NIR + MIR spectral energy distributions

Results


• 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


Circinus


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


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



Results


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)


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


Schartmann et al. (2008)


• 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



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





NGC 7582 ✗ IC 5063 ✔

POLARIZED

BROAD LINES ✔ ✗

i FROM

MODELLING 81°±5°8° 43°±19°

22°

Project





Comparison between RA11+AH11 results and a homogeneous data set of spectropolarimetric data.

Project



• 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



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


GOALS

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Testing the AGN unified model using spectropolarimetry Cristina Ramos Almeida Andrés Asensio Ramos,...

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