Chemical abundances in a UV-selected sample of galaxies
Chemical abundances in a UV-selected sample of galaxies
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DOI：
10.1046/j.1365-8711.2002.05042.x
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发表时间：
2001-09
影响因子：
4.8
通讯作者：
T. Contini;M. Treyer;M. Sullivan;R. Ellis
中科院分区：
文献类型：
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作者：
T. Contini;M. Treyer;M. Sullivan;R. Ellis
我们在物理性质和恒星形成历史的背景下讨论了紫外选择的中红移 (0≲z≲0.4) 星系样本的化学性质。这项工作代表了我们之前对静止框架紫外光度函数（Treyer 等人）和同一样本的恒星形成特性（Sullivan 等人）研究的延伸。我们重新审视这些星系的光谱，并进行进一步的发射线测量，将分析限制在具有导出化学丰度所需的全套发射线的光谱上。我们的最终样本由 68 个星系组成，具有重元素丰度比以及 UV 和 CCD B 波段光度测定。基于发射线比率的诊断表明，我们样本中除一个星系外的所有星系均由炽热的年轻恒星提供动力，而不是活动星系核。将氧与氢 (O/H) 和氮与氧 (N/O) 丰度比与各种局部和中间红移样品的丰度比进行了比较。我们的紫外线选择星系的氧丰度范围很广，从~0.1到1Z⊙，介于低质量H II星系和大质量星暴核之间。对于给定的氧丰度，大多数的 N/O 值都非常低。此外，UV选择星系和H II星系系统地偏离了通常的金属度-光度关系，即亮度增加了2-3星等。采用“延迟释放”化学演化模型，我们建议我们的紫外线选择源在其演化的一个特殊阶段进行观察，在一次强大的星暴之后，该星暴增强了其ISM中的氧气并暂时降低了其质量与光的比率。我们简要讨论我们的结论对类似选择的高红移星系的性质的影响。
We discuss the chemical properties of a sample of UV-selected intermediate-redshift (0≲z≲0.4) galaxies in the context of their physical nature and star-formation history. This work represents an extension of our previous studies of the rest-frame UV-luminosity function (Treyer et al.) and the star-formation properties of the same sample (Sullivan et al.). We revisit the optical spectra of these galaxies and perform further emission-line measurements restricting the analysis to those spectra with the full set of emission lines required to derive chemical abundances. Our final sample consists of 68 galaxies with heavy-element abundance ratios and both UV and CCD B-band photometry. Diagnostics based on emission-line ratios show that all but one of the galaxies in our sample are powered by hot, young stars rather than by an AGN. Oxygen-to-hydrogen (O/H) and nitrogen-to-oxygen (N/O) abundance ratios are compared with those of various local and intermediate-redshift samples. Our UV-selected galaxies span a wide range of oxygen abundances, from ∼0.1 to 1 Z⊙, intermediate between low-mass H II galaxies and massive starburst nuclei. For a given oxygen abundance, most have strikingly low N/O values. Moreover, UV-selected and H II galaxies systematically deviate from the usual metallicity–luminosity relation in the sense of being more luminous by 2–3 mag. Adopting the ‘delayed-release’ chemical evolution model, we propose our UV-selected sources are observed at a special stage in their evolution, following a powerful starburst that enriched their ISM in oxygen and temporarily lowered their mass-to-light ratios. We discuss briefly the implications of our conclusions on the nature of similarly selected high-redshift galaxies.