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arXiv 1102.1740astro-ph.CO
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Lyman Break Analogs:对低高红移极端星暴形成的制约

Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

Thiago S. Gonçalves, Roderik Overzier, Antara Basu-Zych, D. Christopher Martin

摘要:

Lyman Break Analogs(LBA)是低红移宇宙($z\sim 0.2$)中的一个非常活跃的星系,其恒星形成速率是银河系的50倍。这些天体的金属丰度、形态和其他物理性质类似于高红移的Lyman Break Galeries(LBG),激发了对LBA作为高红移星系群的本地实验室的详细研究。我们目前的结果,从我们最近的积分场光谱调查的LBA与凯克/OSIRIS,这表明,这些星系具有相同的星云气体运动学性质的高红移LBG。我们认为,这样的运动学研究本身并不是一个适当的诊断,以排除合并事件作为所观察到的星爆的触发器。HST成像的运动学分析和形态指标之间的比较说明了正确识别(次要或主要)合并事件的困难,使用这两种方法的结果之间没有明确的相关性。我们的数据的人工红移表明,这个问题变得更糟,在高红移由于表面亮度变暗和分辨率损失。合并是否可以产生所观察到的运动学性质是强烈依赖于这些星系中的气体分数。我们提出了初步的CARMA调查结果的LBA和讨论推断的分子气体质量的形成模型的影响。

英文摘要:

Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe ($z\sim 0.2$), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

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