arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1606.01259astro-ph.GA
收藏

[ OIII ]/H $β$与半导体在$z \sim 2$的比星形成率的关系

The Relation Between [OIII]/H$β$ and Specific Star Formation Rate in Galaxies at $z \sim 2$

Claire Mackay Dickey, Pieter van Dokkum, Pascal Oesch, Katherine Whitaker, Ivelina Momcheva, Erica Nelson, Joel Leja, Gabriel Brammer, Marijn Franx, Rosalind Skelton

阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

最近的调查已经确定了一个似乎无处不在的人口与升高的[OIII]/H $β$在$z > 1$发射线比的星系，虽然这种现象的性质仍然存在争议。[OIII]/H $β$谱线比值之所以令人感兴趣，是因为它是区分活动星系核（AGN）和恒星形成星系的标准诊断工具的主要组成部分，以及气相金属丰度指标$O_{23}$和$R_{23}$。在这里，我们调查的主要驱动程序增加[OIII]/H $β$比率的中间叠加静止帧光谱的样本中的恒星形成星系的3D-HST调查的红移范围$z\sim1.4-2.2$。使用$N = 4220$恒星形成星系，我们堆叠的数据在质量和特定的恒星形成率（sSFR）的箱分别。在考虑了恒星的巴耳末吸收后，我们测量了[OIII] $\lambda5007$/H $β$下降到$\mathrm{M} \sim 10^{9.2} \ \mathrm{M_\odot}$和sSFR $\sim 10^{-9.6} \ \mathrm{yr}^{-1}$，比以前在类似红移下的工作低了一个数量级。我们发现一个偏移量的$0.59\pm0.05$德克斯之间的中位数比率在$z\sim2$和$z\sim0$在固定的恒星质量，与现有的研究。然而，关于sSFR，$z \sim 2$堆栈都位于中值SDSS比率的1 $σ$内，平均偏移仅为$-0.06\pm 0.05$。我们发现，星系的激发特性与它们的sSFR在$z\sim2$和$z\sim0$密切相关，在过去的10 Gyr宇宙时间的关系似乎是大致恒定的。

英文摘要：

Recent surveys have identified a seemingly ubiquitous population of galaxies with elevated [OIII]/H$β$ emission line ratios at $z > 1$, though the nature of this phenomenon continues to be debated. The [OIII]/H$β$ line ratio is of interest because it is a main component of the standard diagnostic tools used to differentiate between active galactic nuclei (AGN) and star-forming galaxies, as well as the gas-phase metallicity indicators $O_{23}$ and $R_{23}$. Here, we investigate the primary driver of increased [OIII]/H$β$ ratios by median-stacking rest-frame optical spectra for a sample of star-forming galaxies in the 3D-HST survey in the redshift range $z\sim1.4-2.2$. Using $N = 4220$ star-forming galaxies, we stack the data in bins of mass and specific star formation rates (sSFR) respectively. After accounting for stellar Balmer absorption, we measure [OIII]$\lambda5007$Å/H$β$ down to $\mathrm{M} \sim 10^{9.2} \ \mathrm{M_\odot}$ and sSFR $\sim 10^{-9.6} \ \mathrm{yr}^{-1}$, more than an order of magnitude lower than previous work at similar redshifts. We find an offset of $0.59\pm0.05$ dex between the median ratios at $z\sim2$ and $z\sim0$ at fixed stellar mass, in agreement with existing studies. However, with respect to sSFR, the $z \sim 2$ stacks all lie within 1$σ$ of the median SDSS ratios, with an average offset of only $-0.06\pm 0.05$. We find that the excitation properties of galaxies are tightly correlated with their sSFR at both $z\sim2$ and $z\sim0$, with a relation that appears to be roughly constant over the last 10 Gyr of cosmic time.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑