2015A&A...577A..66M


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.02CET11:56:07

2015A&A...577A..66M - Astronomy and Astrophysics, volume 577A, 66-66 (2015/5-1)

Modeling optical and UV polarization of AGNs. III. From uniform-density to clumpy regions.

MARIN F., GOOSMANN R.W. and GASKELL C.M.

Abstract (from CDS):

A growing body of evidence suggests that some, if not all, scattering regions of active galactic nuclei (AGNs) are clumpy. The inner AGN components cannot be spatially resolved with current instruments and must be studied by numerical simulations of observed spectroscopy and polarization data. We run radiative transfer models in the optical/UV for a variety of AGN reprocessing regions with different distributions of clumpy scattering media. We obtain geometry-sensitive polarization spectra and images to improve our previous AGN models and their comparison with the observations. We use the latest public version 1.2 of the Monte Carlo code stokes presented in the first two papers of this series to model AGN reprocessing regions of increasing morphological complexity. We replace previously uniform-density media with up to thousands of constant-density clumps. We couple a continuum source to fragmented equatorial scattering regions, polar outflows, and toroidal obscuring dust regions and investigate a wide range of geometries. We also consider different levels of fragmentation in each scattering region to evaluate the importance of fragmentation for the net polarization of the AGN. In comparison with uniform-density models, equatorial distributions of gas and dust clouds result in grayer spectra and show a decrease in the net polarization percentage at all lines of sight. The resulting polarization position angle depends on the morphology of the clumpy structure, with extended tori favoring parallel polarization while compact tori produce orthogonal polarization position angles. In the case of polar scattering regions, fragmentation increases the net polarization unless the cloud filling factor is small. A complete AGN model constructed from the individual, fragmented regions can produce low polarization percentages (<2%), with a parallel polarization angle for observer inclinations up to 70° for a torus half opening angle of 60°. For type-2 viewing angles the polarization switches to perpendicular and rises to ∼50%. Our modeling shows that the introduction of fragmented dusty tori significantly alters the resulting net polarization of an AGN. Comparison of our models to polarization observations of large AGN samples greatly favors geometrically compact clumpy tori over extended ones.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: Seyfert - polarization - radiative transfer - scattering

Simbad objects: 12

goto Full paper

goto View the reference in ADS

Number of rows : 12

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4141 2
2 NGC 1365 Sy1 03 33 36.458 -36 08 26.37 10.48 10.08 9.63 8.79 9.7 ~ 1543 2
3 2E 2389 Sy1 11 04 13.8613944317 +76 58 58.192391742   15.70 15.72 15.40   ~ 511 1
4 NGC 3516 Sy1 11 06 47.4596406816 +72 34 07.189563769   13.12 12.40     ~ 1426 0
5 3C 256 rG 11 20 43.022 +23 27 55.21   21.5       ~ 118 0
6 Mrk 231 Sy1 12 56 14.2340989340 +56 52 25.238555193   14.68 13.84     ~ 1800 3
7 ESO 323-77 Sy2 13 06 26.1213873662 -40 24 52.594127368   13.58 13.42 12.01   ~ 193 0
8 ESO 383-35 Sy1 13 35 53.7686909139 -34 17 44.139127597   13.89 13.61 8.9   ~ 1389 0
9 NAME Circinus Galaxy Sy2 14 13 09.906 -65 20 20.47   10.89 9.84 10.6 10.0 ~ 1025 2
10 3C 324.0 Sy1 15 49 48.9 +21 25 38   21.5       ~ 300 0
11 ESO 140-43 Sy1 18 44 53.9893682398 -62 21 52.871742814   14.14 14.10 12.94 13.1 ~ 215 0
12 NAME MR 2251-178 Sy1 22 54 05.8858021308 -17 34 55.403006841   14.99 14.36 15.12   ~ 379 3

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2015A&A...577A..66M and select 'bookmark this link' or equivalent in the popup menu


2020.12.02-11:56:07

© Université de Strasbourg/CNRS

    • Contact