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arXiv 0811.4694astro-ph
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局域红外选择星系的恒星星族分析

Stellar population analysis on local infrared-selected galaxies

X. Y. Chen, Y. C. Liang, F. Hammer, Y. H. Zhao, G. H. Zhong

摘要:

研究近红外星系的恒星星族,包括恒星形成星系、复合星系、LINER星系和Seyfert 2星系。我们还想知道红外光度和光谱类是否对它们的恒星星族有任何影响。样本星系是从SDSS-DR4的主星系样本中选取的,然后与IRAS-PSCz星表进行了交叉相关。在简单恒星星族模板和星团光谱的基础上,用STARLIGHT光谱合成程序拟合了我们的光谱(恒星吸收线和连续谱),在4个光谱类中,LINER代表了最古老的恒星星族,其他3个子样本都代表了大量的年轻和中等年龄的恒星族,只有很少的老年恒星族。年轻族群的重要性从恒星形成、合成、Seyfert 2到LINER逐渐降低。对于不同的红外光度箱,ULIGs和LIGs(log($L_{IR}/L_{\odot})\geq$ 11))比星暴和正常星系呈现出更年轻的星群。然而,在所有样本星系中,质量的主要贡献者都是老年人。以不同年龄和金属丰度的星团光谱为模板进行拟合,也得到了一致的结果。在恒星形成星系和复合星系中占主导地位的是那些金属丰度为$Z=0.2Z_\odot$的星系,而LINER和Seyfert 2的金属丰度更高。在不同的红外光度箱中,正常星系比ULIGs和LIGs以及恒星爆发中的恒星形成星系更富金属。此外,我们还比较了一些合成结果与其他参数从MPA/JHU目录。

英文摘要:

To study the stellar population of local infrared galaxies, which contain star-forming galaxies, composite galaxies, LINERs, and Seyfert 2s. We also want to find whether infrared luminosity and spectral class have any effects on their stellar populations. The sample galaxies are selected from the main galaxy sample of SDSS-DR4 and then cross-correlated with the IRAS-PSCz catalog. We fit our spectra (stellar absorption lines and continua) using the spectral synthesis code STARLIGHT on the base of the templates of Simple Stellar Population and the spectra of star clusters.Among the 4 spectral classes, LINERs present the oldest stellar populations, and the other 3 sub-samples all present substantial young and intermediate age populations and very few old populations. The importance of young populations decreases from star-forming, composite, Seyfert 2 to LINER. As to different infrared luminosity bins, ULIGs & LIGs (log($L_{IR}/L_{\odot})\geq$11) present younger populations than starbursts and normal galaxies. However, the dominant contributors to mass are old populations in all sample galaxies. The fittings by using the spectra of star clusters with different ages and metallicities as templates also give consistent results. The dominated populations in star-forming and composite galaxies are those with metallicity $Z=0.2Z_\odot$, while LINERs and Seyfert 2s are more metal-rich. The normal galaxies are more metal-rich than the ULIGs & LIGs and starbursts for the star-forming galaxies within different infrared luminosity bins. Additionally, we also compare some synthesis results with other parameters obtained from the MPA/JHU catalog.

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