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arXiv 1503.03977astro-ph.GA
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双星相互作用对早型星系参数测定的影响

The effects of binary interactions on parameter determinations for early-type galaxies

Yu Zhang, Jinzhong Liu, Fenghui Zhang

摘要:

基于不含(SSP)和含(BSP)双星相互作用的恒星星族模型,研究了双星相互作用对早型星系(ETG)参数测定的影响。我们提出光度红移(photo-z),年龄和光谱类型的光度数据样本拟合观测震级与SSP和BSP模型。我们的研究结果表明,二进制相互作用没有影响photo-z估计。当忽略双星相互作用时,ETG的年龄将被低估,而对于其他类型的星系,其年龄估计的影响可以忽略不计。对于ETG样品,我们通过用SSP和BSP模型拟合它们的光谱得到了它们的性质。当比较这些星系的属性,我们发现没有变化的整体金属丰度之间的SSP和BSP模型的ETG。此外,包含二元相互作用可能会影响年龄估计。结果表明,约33.3%的ETG样品的BSP拟合年龄比SSP拟合年龄大0.5-1.0 Gyr,约44.2%的样品仅比SSP拟合年龄大0.1-0.5 Gyr,其余约22.5%的样品基本相等。通过比较,我们发现在演化后期,SSP和BSP模型的恒星形成率差异较大。

英文摘要:

Based on stellar population models without (SSP) and with (BSP) binary interactions, we investigate the effects of binary interactions on parameter determinations for early-type galaxies (ETGs). We present photometric redshift (photo-z), age and spectral type for photometric data sample by fitting observed magnitudes with the SSP and BSP models. Our results show that binary interactions have no effect on photo-z estimation. Once we neglect binary interactions, the age of ETGs will be underestimated, by contrast, the effects on the age estimations can be negligible for other type of galaxies. For ETG sample, we derive their properties by fitting their spectra with the SSP and BSP models. When comparing these galaxy properties, we find no variation of the overall metallicities for ETGs among the SSP and BSP models. Moreover, the inclusion of binary interactions can affect age estimations. Our results show that the BSP-fitted ages in ~33.3% of ETG sample are around 0.5-1.0 Gyr larger than the SSP-fitted ages; ~44.2\% are only 0.1-0.5 Gyr larger; the rest ~22.5% are approximately equal. By comparisons, we find the difference of the star formation rate between the SSP and BSP models is large at the late evolution stage.

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