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arXiv 1301.7501astro-ph.CO
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用AKARI InfraRed相机研究硬X射线选择活动星系核的2.5 - 5 μ m光谱

A 2.5-5 μm Spectroscopic Study of Hard X-ray Selected AGNs using AKARI InfraRed Camera

A. Castro, T. Miyaji, T. Nakagawa, M. Shirahata, S. Oyabu, M. Imanishi, Y. Ueda, K. Ichikawa

摘要:

本文介绍了利用红外天文卫星AKARI上的红外照相机(IRC)的棱镜模式对硬X射线选择的活动星系核(AGN)样品进行2.5 - 5 μ m光谱测量的结果。样本是从9个月的斯威夫特/BAT调查在14 - 195 keV波段,这提供了一个公平的样本,包括高吸收的活动星系核。2.5 - 5 μ m光谱通过3.3 μ m的多环芳烃(PAH)发射和3.1 μ m的H2O冰、3.4 μ m的裸露碳质尘埃、4.26 μ m的CO2和4.67 μ m的CO吸收等连续的形态和发射/吸收特征,为AGN的环核环境提供了强有力的诊断工具。作为我们的第一步,我们使用3.3 μ mPAH辐射作为恒星形成活动的替代,并寻找1型(未吸收)和2型(吸收)活动星系核之间恒星形成活动的可能差异。我们发现3.3 μ mPAH谱线的亮度(用黑洞质量归一化)与活动星系核的光学类型或X射线测量的柱密度没有明显的依赖关系。

英文摘要:

We present results of the 2.5-5 μm spectroscopy of a sample of hard X-ray selected active galactic nuclei (AGNs) using the grism mode of the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI. The sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band, which provides a fair sample of AGNs including highly absorbed ones. The 2.5-5 μm spectroscopy provide a strong diagnostic tool for the circumnuclear environment of AGNs through the continuum shapes and emission/absorption features such as the 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission and the broad 3.1 μm H2O ice, 3.4 μm bare carbonaceous dust, 4.26 μm CO2 and 4.67 μm CO absorptions. As our first step, we use the 3.3 μm PAH emission as a proxy for the star-formation activity and searched for possible difference of star-formation activity between type 1 (unabsorbed) and type 2 (absorbed) AGNs. We found no significant dependence of the 3.3 μm PAH line luminosity, normalized by the black hole mass, on optical AGNs types or the X-ray measured column densities.

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