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arXiv 0802.2458astro-ph
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AGN中尘埃环的性质:I. SWIRE/SDSS类星体的情况

Properties of dusty tori in AGN: I. The Case of SWIRE/SDSS Quasars

E. Hatziminaoglou, J. Fritz, A. Franceschini, A. Afonso-Luis, A. Hernan-Caballero, I. Perez-Fournon, S. Serjeant, C. Lonsdale, S. Oliver, M. Rowan-Robinson, D. … 展开作者

E. Hatziminaoglou, J. Fritz, A. Franceschini, A. Afonso-Luis, A. Hernan-Caballero, I. Perez-Fournon, S. Serjeant, C. Lonsdale, S. Oliver, M. Rowan-Robinson, D. Shupe, H. E. Smith, J. Surace

摘要:

通过比较观测到的SDSS类星体的光谱能量分布和预先计算的环面模型网格,我们得到了活动星系核(AGN)中尘埃环面的性质。观测到的SED包括SDSS测光,2MASS J,H和K数据,以及来自斯皮策广域红外河外(SWIRE)巡天的中红外(MIR)数据。采用的模型是Fritz等人的模型,2006.拟合是通过标准的卡方平方最小化来完成的,然而,只要有必要,模型也可以是多分量的,包括恒星分量和星暴分量。允许低赤道光学厚度的模型,tau_9.7,以及tau_9.7 > 1.0的“传统”模型,对应于A_V > 22,并对结果进行了比较。使用高光学深度环面模型的拟合仅产生比允许所有tau_9.7模型的配置中更致密分布的灰尘。随着离中心的距离,灰尘密度逐渐降低的Tori受到青睐,而对于灰尘密度有或没有角度变化的模型没有明显的偏好。计算的环面的外半径是几十秒差距,但在少数情况下,可以达到几百秒差距。尘埃的质量,M_Dust,和红外光度,L_IR,在1和1000微米之间的波长范围内集成,不显示出显着的变化与红移,一旦观测偏差被考虑在内。70微米的检测对象,代表25%的样品,分别研究和星爆的贡献(无论何时)的红外光度可以达到,在最极端的情况下,但很少的情况下,80%。

英文摘要:

We derive the properties of dusty tori in Active Galactic Nuclei (AGN) from the comparison of observed Spectral Energy Distributions (SEDs) of SDSS quasars and a precomputed grid of torus models. The observed SEDs comprise SDSS photometry, 2MASS J, H, and K data, whenever available and mid-Infrared (MIR) data from the Spitzer Wide-area InfraRed Extragalactic (SWIRE) Survey. The adopted model is that of Fritz et al., 2006. The fit is performed by standard chi^2 minimisation, the model however can be multi-component comprising a stellar and a starburst components, whenever necessary. Models with low equatorial optical depth, tau_9.7, were allowed as well as ``traditional'' models with tau_9.7 > 1.0, corresponding to A_V > 22 and the results were compared. Fits using high optical depth tori models only produced dust more compactly distributed than in the configuration where all tau_9.7 models were permitted. Tori with decreasing dust density with the distance from the centre were favoured while there was no clear preference for models with or without angular variation of the dust density. The computed outer radii of the tori are of some tens of parsecs large but can reach, in a few cases, a few hundreds of parsecs. The mass of dust, M_Dust, and infrared luminosity, L_IR, integrated in the wavelength range between 1 and 1000 micron, do not show significant variations with redshift, once the observational biases are taken into account. Objects with 70 micron detections, representing 25% of the sample, are studied separately and the starburst contribution (whenever present) to the IR luminosity can reach, in the most extreme but very few cases, 80%.

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