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arXiv 1407.6005astro-ph.GA
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作为WISE I:在3.4和4.6微米处验证恒星星族模型和M/L比率

Being WISE I: Validating Stellar Population Models and M/L ratios at 3.4 and 4.6 microns

Mark A. Norris, Sharon Meidt, Glenn Van de Ven, Eva Schinnerer, Brent Groves, Miguel Querejeta

摘要:

利用来自WISE任务的数据,我们测量了金属丰度范围为-2.2 < [Fe/H](dex)< 0.3的各种无尘恒星系统(球状星团、矮星系和巨早型星系)的近红外(NIR)测光。这极大地增加了样品的大小,并扩大了金属度制度,其中3.4(W1)和4.6微米(W2)测光的恒星星族已被检查。我们发现中老(> 2 Gyr)恒星星族的W1 - W2色对恒星星族的年龄不敏感,但W1 - W2色随着金属丰度的增加而变蓝,这一趋势在大多数恒星星族合成(SPS)模型中不能很好地再现.与以前的研究一样,我们将这种行为归因于位于4.6微米带通的CO吸收特征的强度增加。在使用我们的样本来验证一些SPS模型的有效性后,我们使用这些模型来推导W1和W2波段的恒星质光比。利用观测数据的SAURON和ATLAS 3D调查,我们证明,这些波段提供了非常简单,但强大的恒星质量示踪剂的无尘老年恒星星族,是免费的光学估计之间的许多共同的不确定性。

英文摘要:

Using data from the WISE mission, we have measured near infra-red (NIR) photometry of a diverse sample of dust-free stellar systems (globular clusters, dwarf and giant early-type galaxies) which have metallicities that span the range -2.2 < [Fe/H] (dex) < 0.3. This dramatically increases the sample size and broadens the metallicity regime over which the 3.4 (W1) and 4.6 micron (W2) photometry of stellar populations have been examined. We find that the W1 - W2 colors of intermediate and old (> 2 Gyr) stellar populations are insensitive to the age of the stellar population, but that the W1 - W2 colors become bluer with increasing metallicity, a trend not well reproduced by most stellar population synthesis (SPS) models. In common with previous studies, we attribute this behavior to the increasing strength of the CO absorption feature located in the 4.6 micron bandpass with metallicity. Having used our sample to validate the efficacy of some of the SPS models, we use these models to derive stellar mass-to-light ratios in the W1 and W2 bands. Utilizing observational data from the SAURON and ATLAS3D surveys, we demonstrate that these bands provide extremely simple, yet robust stellar mass tracers for dust free older stellar populations that are freed from many of the uncertainties common among optical estimators.

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