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arXiv 0708.2877astro-ph
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塞弗特星系的中红外辐射。ISOCAM数据的新分析

The mid-infrared emission of Seyfert galaxies. A new analysis of ISOCAM data

Cristina Ramos Almeida, Ana Maria Perez Garcia, Jose Antonio Acosta-Pulido, Jose Miguel Rodriguez Espinosa

摘要:

我们目前的中红外数据的样本57 AGN获得的仪器ISOCAM上的卫星ISO。通过LW 2(6.75微米)和LW 7(9.62微米)滤光片获得图像。这是对Clavel等(2000)星系样本的新分析,该样本被分为26个1型(≤ 1.5)和28个2型(> 1.5)Seyfert星系,外加3个类星体。图像的空间分辨率使我们能够在将亮度分布分解为不同的形态成分后,将核和扩展贡献分离到总发射。最常见的组成部分是一个中心点源(确定为活动核)和一个指数盘。在某些情况下,需要一个凸起,一个酒吧或一个环。在塞弗特1中,原子核对总发射的相对贡献似乎大于塞弗特2。这一结果证实了这两种类型的塞弗特星系是不同的中红外和支持存在的结构,产生各向异性的发射在这个波长范围内。我们还探讨了中红外线与无线电和X射线波长范围之间的相关性。在我们的样品中,星系的全球辐射保持了良好的无线电/红外相关性。如果只考虑核红外辐射,则在光度-光度散点图中存在明显的非线性相关。内禀硬X射线和核中红外辐射之间的比值呈现出较大的散射和略大的值为2型塞弗特星系。这些结果似乎与围绕活动核的尘埃环的存在是一致的。

英文摘要:

We present mid-infrared data of a sample of 57 AGNs obtained with the instrument ISOCAM on board the satellite ISO. The images were obtained through the LW2 (6.75 microns) and LW7 (9.62 microns) filters. This is a new analysis of Clavel et al. (2000) galaxy sample, which is divided into 26 type 1 (< or = 1.5) and 28 type 2 (> 1.5) Seyfert galaxies, plus three QSOs. The spatial resolution of the images allow us to separate the nuclear and the extended contributions to the total emission after decomposing the brightness profiles into different morphological components. The most common components are a central point source (identified as the active nucleus) and an exponential disk. In some cases a bulge, a bar or a ring are needed. The relative contribution of the nucleus to the total emission appears larger in Seyfert 1 than in Seyfert 2. This result confirms that both types of Seyfert galaxies are different in the mid-infrared and supports the existence of an structure which produces anisotropic emission in this wavelength range. We have also explored correlations between the mid-infrared and the radio and X-ray wavelength ranges. The well established radio/infrared correlation is mantained in our sample for the global emission of the galaxies. If only the nuclear infrared emission is considered then a non-linear correlation is apparent in the luminosity-luminosity scatter diagram. The ratio between the intrinsic hard X-ray and the nuclear mid-infrared emission presents large scatter and slightly larger values for type 2 Seyfert galaxies. These results seem to be consistent with the presence of a clumpy dusty torus surrounding the active nucleus.

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