论文标题
遗物星系NGC〜1277排除了大型早期型星系中共同吸收的中级恒星种群的起源
The relic galaxy NGC~1277 rules out intermediate-age stellar populations origin of CO-strong absorptions in massive early-type galaxies
论文作者
论文摘要
大量的早期型星系（ETG）在其H和K频段光谱中显示出几种强大的CO吸收特征，这些特征无法通过最先进的恒星种群模型来解释。多年来，分歧一直归因于中等年龄的恒星成分，这些成分由渐近巨型分支（AGB）阶段中的恒星主导。但是，到目前为止，尚未提供这种情况的强大证据。测试该主张的一种方法是比较ETG和遗物星系的CO指数。遗物星系缺乏中级恒星种群，为我们提供了一个独特的机会，可以解决ETG中强CO吸收的起源。在这里，我们利用了原型遗物Galaxy NGC 1277，并将该星系的CO吸收特征与代表性的大型ETG样品的CO吸收特征进行了比较。我们表明，这两个系统中的CO线都具有相似的优势，明显强大，比出色的种群合成模型的预测更强大。我们得出的结论是，大量ETG中的中级恒星种群不是强大的CO吸收的罪魁祸首。
Massive Early-Type Galaxies (ETGs) show several strong CO absorption features in their H- and K-band spectra that cannot be explained by state-of-the-art stellar population models. For many years, the disagreement has been attributed to the presence of intermediate-age stellar components that are dominated by stars in the Asymptotic Giant Branch (AGB) phase. However, no robust evidence of this scenario has been provided so far. One way to test this claim is by comparison of CO indices for ETGs and for relic galaxies. Lacking the intermediate-age stellar populations, relic galaxies provide us with a unique opportunity to address the origin of strong CO absorptions in ETGs. Here, we utilize the prototype relic galaxy NGC 1277 and compare the CO absorption features of this galaxy with the ones of a representative sample of massive ETGs. We show that the CO lines in both systems have similar strengths, significantly stronger than the predictions of stellar population synthesis models. We conclude that intermediate-age stellar populations in massive ETGs are not the culprit of the strong CO absorptions.
