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arXiv 1306.5759astro-ph.CO
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硬X射线活动星系核样品的恒星星族性质

Stellar population properties for a sample of hard X-ray AGNs

L. Morelli, V. Calvi, N. Masetti, P. Parisi, R. Landi, E. Maiorano, D. Minniti, G. Galaz

摘要:

本文的目的是研究具有活动星系核(AGN)的星系的恒星星族。我们研究了INTEGRAL和Swift星表中的一个子样本,这些子样本是以前通过光谱学鉴定和表征的硬X射线发射活动星系核。我们的分析提供了补充信息,即年龄和金属丰度,这是完成这些有趣物体的全景所必需的。我们选择了硬X射线发射对象确定为活动星系核,通过检查他们的光谱,在寻找适合的吸收线的恒星星族分析。我们最终获得了一个由20个红移小于0.3的天体组成的样本。我们使用了全谱拟合方法,特别是惩罚像素的应用PPXF代码。在屏蔽了所有受发射线影响的区域后,我们用MILES单恒星星族模板拟合光谱,并推导出质量加权年龄和金属丰度。我们样本中的大多数天体都显示出古老的恒星星族,但其中三个天体的特征是双峰分布,年轻恒星的贡献不可忽略。质量加权金属丰度的值跨越了很大的金属丰度范围,其中大多数略高于太阳值。没有发现恒星星族性质与形态性质之间的关系。

英文摘要:

The aim of this paper is to study the stellar population of galaxies hosting an active galactic nucleus (AGN). We studied a sub-sample of hard X-ray emitting AGNs from the INTEGRAL and Swift catalogs which were previously identified and characterized through optical spectroscopy. Our analysis provides complementary information, namely age and metallicity, which is necessary to complete the panoramic view of such interesting objects. We selected hard X-ray emitting objects identified as AGNs by checking their optical spectra in search for absorption lines suitable for the stellar population analysis. We obtained a final sample consisting of 20 objects with redshift lower than 0.3. We used the full-spectrum fitting method and, in particular, the penalized pixel one applying the PPXF code. After masking all the regions affected by emission lines, we fitted the spectra with the MILES single stellar population templates and we derived mass-weighted ages and metallicities. Most of the objects in our sample show an old stellar population, but three of them are characterized by a bimodal distribution with a non negligible contribution from young stars. The values of the mass-weighted metallicity span a large range of metallicity with most of them slightly above the solar value. No relations between the stellar population properties and the morphological ones have been found.

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