期刊
ASTROPHYSICAL JOURNAL
卷 731, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/731/2/92
关键词
galaxies: active; galaxies: nuclei; galaxies: Seyfert; infrared: galaxies
资金
- Spanish Ministry of Science and Innovation (MICINN) [CSD2006-00070, AYA2007-63881, AYA2008-06311-C02-01]
- STFC PDRA [ST/G001758/1]
- Spanish Plan Nacional del Espacio [ESP2007-65475-C02-01]
- Plan Nacional de Astronomia y Astrofisica [AYA2009-05705-E]
- NSF [0904421]
- STFC [ST/G001758/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/G001758/1] Funding Source: researchfish
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [0904421, 904896] Funding Source: National Science Foundation
We present new mid-infrared imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample studied in a previous work to compare the properties of Type-1 and Type-2 Seyfert tori using clumpy torus models and a Bayesian approach to fit the infrared (IR) nuclear spectral energy distributions. Thus, the sample considered here comprises 7 Type-1, 11 Type-2, and 3 intermediate-type Seyferts. The unresolved IR emission of the Seyfert 1 galaxies can be reproduced by a combination of dust heated by the central engine and direct active galactic nucleus (AGN) emission, while for the Seyfert 2 nuclei only dust emission is considered. These dusty tori have physical sizes smaller than 6 pc radius, as derived from our fits. Unification schemes of AGN account for a variety of observational differences in terms of viewing geometry. However, we find evidence that strong unification may not hold and that the immediate dusty surroundings of Type-1 and Type-2 Seyfert nuclei are intrinsically different. The Type-2 tori studied here are broader, have more clumps, and these clumps have lower optical depths than those of Type-1 tori. The larger the covering factor of the torus, the smaller the probability of having a direct view of the AGN, and vice versa. In our sample, Seyfert 2 tori have larger covering factors (C-T = 0.95 +/- 0.02) and smaller escape probabilities (P-esc = 0.05% +/- (0.08)(0.03)%) than those of Seyfert 1 (C-T = 0.5 +/- 0.1; P-esc = 18% +/- 3%). All the previous differences are significant according to the Kullback-Leibler divergence. Thus, on the basis of the results presented here, the classification of a Seyfert galaxy as a Type-1 or Type-2 depends more on the intrinsic properties of the torus rather than on its mere inclination toward us, in contradiction with the simplest unification model.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据