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arXiv 0909.4312astro-ph.CO
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Seyfert星系的恒星星族探测:近红外透视

Probing the stellar population of seyfert galaxies: a near infrared perspective

R. Riffel, M. G. Pastoriza, A. Rodriguez-Ardila, C. Bonatto

摘要:

我们利用IRTF SpeX近红外光谱(0.8- 2.4 μ m)研究了9个Sy 1和15个Sy 2星系的恒星星族(SP)、活动星系核(AGN)、无特征连续体(FC)和热尘的性质。{ \sc starlight}代码和作为附加基本元素的热尘埃都是第一次在这个光谱范围内使用。我们的合成显示了Sy 1和Sy 2星系之间的显着差异:热尘成分需要符合约90%的Sy 1星系的K带光谱,只有约25%的Sy 2星系;约50%的Sy 2星系需要FC成分贡献>20%;这一比例在Sy 1中增加到约60%。在大约50%的Sy 2中,FC和年轻成分的组合贡献超过20%,而这发生在90%的Sy 1中,这表明中心区域最近有恒星形成。我们星系样本的中央几百秒差距包含相当大一部分的中间年龄SP,其平均金属丰度接近太阳。我们的SP合成证实了1.1微米CN带可以作为中间年龄恒星星族的示踪物。

英文摘要:

We employ IRTF SpeX NIR (0.8--2.4mu m) spectra to investigate the stellar population (SP), active galactic nuclei (AGN), featureless continuum (FC) and hot dust properties in 9 Sy1 and 15 Sy2 galaxies. Both the {\sc starlight} code and the hot dust as an additional base element were used for the first time in this spectral range. Our synthesis shows significant differences between Sy1 and Sy2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy1 galaxies, and only of ~25% of the Sy2; about 50% of the Sy2 galaxies require an FC component contribution >20%; this fraction increases to about 60% in the Sy1. In about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Our SP synthesis confirms that the 1.1microns CN band can be used as a tracer of intermediate-age stellar populations.

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