# Radiative Tranfer modeling of NGC1068 using the Near and Mid IR VLTI data

Niklas Moszczynski, Yann Clénet, James Leftley, Romain Petrov, Pierre Vermot

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Niklas Moszczynski, Yann Clénet, James Leftley, Romain Petrov, Pierre Vermot. Radiative Tranfer modeling of NGC1068 using the Near and Mid IR VLTI data. MASCA: Multi-wavelength AGN Structure and Cosmological Applications, James Leftley and Romain Petrov, Oct 2023, Nice, France. hal-05133633

HAL Id: hal-05133633

https://hal.science/hal-05133633v1

Submitted on 27 Jun 2025

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# Radiative Transfer modeling of NGC1068 using the Near and Mid IR VLTI data

Niklas Moszczyński,

Yann Clénet, James Leftley, Romain Petrov, Pierre Vermot

LESIA & Laboratoire J.-L. Lagrange

<figure><img src="image_3.png" /></figure>
* AGN Unification Model

* Approach: Numerical Radiative Transfer tool, SKIRT

* Impact of radiative dust destruction in numerical modeling

* Radiative Transfer modeling of NGC1068

* Future work/prospects
# AGN Unification model

* **AGN Unification Model:**
  Properties relies on the inclination angle (Antonucci, 1993)

* **Clumps/non smooth dust:**

- Theory suggests toroidal structure with dust in clumps, eg. Krolik and Begelman (1988), Pier and Krolik (1992)

- Near and MID IR data support clumpy medium using RT eg. Nenkova et al. 2002, 2008 (IR), Hönig et al. 2006

* **Polar outflows and winds:**

- MID IR Interferometry data suggest outflows eg. Tristram et al. 2014, Leftley et al. 2018

- Hönig 2019

<figure><img src="image_4.png" /><figcaption>AGN torus model
(Urry & Padovani, 1995)</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>AGN schematic view:
Disk + wind
(Hönig 2019)</figcaption></figure>
# Approach:
## Numerical Radiative Transfer tool, SKIRT

<figure><img src="image_6.png" /></figure>

© Astronomical Observatory, Ghent University.

* SKIRT (Camps and Baes 2020, ascl: 1109.003):

* MC simulation emits photons from point like source in simulation grid with user defined medium.

* Solves the radiative transfer equation using absorption, scattering and re-emission

* Dust destruction feature:

* Removes grain particles from simulation based on average temperature

* Solves the radiative transfer equation: absorption, scattering and re-emission + **Dust destruction**

* Sublimation temperature of dust species, $T_s$

* Sublimation: $T_{eq} > T_s$

<figure><img src="image_7.png" /></figure>

Visual representation of RT MC simulation (Steinacker et al. 2013)

* Compared AGN radiative dust destruction vs no dust destruction in dusty medium
General modelling for AGN

- Large scale (geometry) parameters

- Clumpy torus + Dusty wind (bicone wind):

- Small scale (dust properties) parameters

- Sublimation temperature, grain size interval, grain size distribution

- Following the input of Leftley et al. in prep, for the wind and torus. Dust species: Graphite and Olivine, MRN (Mathis, Rumpl & Nordsieck 1977) power law (α=-3.5). *Model exploration currently too slow*

<figure><img src="image_8.png" /><figcaption>Schematic of torus in SKIRT
(Stalevski et al. 2012)</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>Clumpy torus + bicone</figcaption></figure>
* Temperature profile described by a power law, Independent of dust composition.

$$T(r) \sim r^p, p < 0$$

<figure><img src="image_10.png" /></figure>
# Temperature map: Dust destruction enabled

Temperature profile described by a 'Broken power law' :

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

$T(r)$

$r^p, r > r_b, p < 0$

$r^q, r > r_s \& r < r_b, q < 0$
Temperature maps: Dust destruction enabled

Temperature maps for large and small dust grains of same dust species.

<figure><img src="image_13.png" /><figcaption>Smallest grains (Graphite)</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>Largest grains (Graphite)</figcaption></figure>
# Temperature profile: Dust destruction enabled

<figure><img src="image_15.png" /><figcaption>Broken power law (two grains):</figcaption></figure>

<figure><img src="image_16.png" /></figure>

Articles mentioning non constant slope or grain radius dependent temperature in AGN dust: Interferometry NGC1068 (Gamez-Rosas et al 2022), RT modelling (Hönig et al. 2017), Theory of dust physics (Barvainis 1987)
Data for analysis of NGC1068

* Using GRAVITY UT data (Gravity collaboration 2017, Gravity collaboration 2020) and Matisse data (Lopez B., Lagarde S., Petrov R. G., Jaffe W. et al. 2022, Gamez-Rosas et al. 2022) for modelling NGC1068.

<figure><img src="image_17.png" /><figcaption>* Image reconstruction of NGC1068 using Matisse data (Gamez-Rosas et al. 2022)</figcaption></figure>

<figure><img src="image_18.png" /><figcaption>* Image reconstruction of NGC1068 using GRAVITY data (Gravity collaboration 2020)</figcaption></figure>
* Results from Leftley et al in prep with image reconstructions bottom row (Gamez-Rosas et al 2022). Model gridding currently too slow.

<figure><img src="image_19.png" /></figure>
* Dust destruction enabled (Model+Beam Convolved Model)

<figure><img src="image_20.png" /><figcaption>K-band (2.1 µm), M (3.7µm), L (4.77 µm), N short (8.5µm), N long (11.5 µm)</figcaption></figure>
# Summary, Conclusion and Outlook

* Ongoing work: Find global minimum of χ2 contour plots. Compare with geometric modeling in Nice. Broken temperature power law has already been used in the geometrical model and made it easier to make the poly chromatic fit. Allows to test if radiative dust destruction is valid.

* Enabling radiative dust destruction → broken power law. Larger grains survives closer to the CE.

* Fit both disk/ring structure and disk+wind in K band.