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arXiv 2101.01481astro-ph.GA
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主星系和AGN不同类型星系的方位差异

Host galaxy and orientation differences between AGN different types

Anamaria Gkini, Manolis Plionis, Maria Chira, Elias Koulouridis

摘要:

目的:本研究的主要目的是调查关于活动星系核(AGN)统一范式(UP)的有效性方面。特别是,我们专注于活动星系核的宿主星系,根据UP应该没有系统的差异取决于活动星系核的分类。方法:为了这项研究的目的,我们使用(a)光谱斯隆数字巡天(SDSS)数据发布(DR)14目录,为了选择和分类AGN使用发射线诊断,z=0.2的红移,和(b)银河动物园项目目录,其中分类SDSS星系在两个广泛的哈勃类型:螺旋和椭圆。结果:我们发现,1型塞弗特核(Sy1)在椭圆星系中的比例明显大于任何其他类型活动星系核的相应比例,而从Sy1到LINER,2型塞弗特核(Sy2)和复合核的螺旋宿主有一个梯度。这些发现不能用简单的统一模型来解释,而可能是用超大质量黑洞(SMBH)和星系凸起的共同演化方案来解释。此外,对于螺旋宿主星系的情况下,我们发现的Sy1人口强烈倾向于面对配置,而相应的Sy2人口范围内的所有宿主星系的方向配置有一个类似的,但不相同的,方向分布的恒星形成(SF)星系。这些结果也不能用标准的统一范式来解释,但却指向了银盘对核区域的遮蔽的重要贡献。这也与观察到的Sy1核被椭圆星系托管的偏好一致,也就是说,螺旋宿主的尘埃盘有助于宽线区(BLR)的模糊,因此预计会出现相对更多的椭圆星系托管Sy1核。

英文摘要:

Aims.The main purpose of this study is to investigate aspects regarding the validity of the active galactic nucleus (AGN) unification paradigm (UP). In particular, we focus on the AGN host galaxies, which according to the UP should show no systematic differences depending on the AGN classification. Methods.For the purpose of this study, we used (a) the spectroscopic Sloan Digital Sky Survey (SDSS) Data Release (DR) 14 catalogue, in order to select and classify AGNs using emission line diagnostics, up to a redshift of z=0.2, and (b) the Galaxy Zoo Project catalogue, which classifies SDSS galaxies in two broad Hubble types: spirals and ellipticals. Results.We find that the fraction of type 1 Seyfert nuclei (Sy1) hosted in elliptical galaxies is significantly larger than the corresponding fraction of any other AGN type, while there is a gradient of increasing spiral-hosts from Sy1 to LINER, type 2 Seyferts (Sy2) and composite nuclei. These findings cannot be interpreted within the simple unified model, but possibly by a co-evolution scheme for supermassive black holes (SMBH) and galactic bulges. Furthermore, for the case of spiral host galaxies we find the Sy1 population to be strongly skewed towards face-on configurations, while the corresponding Sy2 population range in all host galaxy orientation configurations has a similar, but not identical, orientation distribution to star-forming (SF) galaxies. These results also cannot be interpreted by the standard unification paradigm, but point towards a significant contribution of the galactic disc to the obscuration of the nuclear region. This is also consistent with the observed preference of Sy1 nuclei to be hosted by ellipticals, that is, the dusty disc of spiral hosts contributes to the obscuration of the broad-line region (BLR), and thus relatively more ellipticals are expected to appear hosting Sy1 nuclei.

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