论文标题
[oiii] $+$ h $β$等效的宽度分布在z $ \ simeq $ 7：对星系贡献的贡献的影响
The [OIII]$+$H$β$ Equivalent Width Distribution at z$\simeq$7: Implications for the Contribution of Galaxies to Reionization
论文作者
论文摘要
我们使用20个明亮的样本（m $ _ {\ mathrm {uv}} $ $ $ $ $ $ $ $ $ $ $ - $ - $ 21）Galaxies量化了[OIII]+H $β$线强度的分布。我们使用新的颜色选择选择这些系统，而不是宽面积（2.3 v $^2 $），该系统精确地选择了z $ \ simeq $ 6.63 $ 6.63 $ - $ 6.83的星系，蓝色spitzer/irac/irac [3.6] $ - $ [4.5] colors nomambigully colorsive and ambigully colorsive nocige and ambigully colorsive strong [oiii] $ $ $ y $ h。这20个星系表明，log-Normalal [oiii] $+$ h $β$ ew分布，中间ew = 759 $^{+112} _ { - 113} $ $ $ $ \ sathrm {\ mathring {\ mathring {a}}} $ and standard deviation and standard deviation = 0.26 $^{+0.26 $^{+0.06 $ 0.06} _.00.00.00.0.00.00.05.05.00.05.00.05.05.05.05}我们发现没有证据表明这种EW分布中有紫外线发光度有很大差异。我们的样本所暗示的典型[OIII]+H $β$ ew at z $ \ simeq $ 7比在Z $ \ Simeq $ 2的大型星系中形成星系中的典型[oiii]+h $β$ 7，这与朝着更大的平均ssfr（4.4 Gyr $^{ - 1} $} $ \ simeq $ 2相一致，并且低位金属（0.16 z $ ____）。我们还发现证据表明，人口的出现更加极端的变形（[OIII]+H $β$ ew $> $ 1200 $ \ MATHRM {\ MATHRING {a}} $）很少在低红移。这些对象具有极大的SSFR（$> $ 30 GYR $^{ - 1} $），正如在恒星形成中发生爆发或上升的系统所期望的那样。尽管这可能是一个短暂的阶段，但我们的结果表明，Z $ \ simeq $ 7人口中有20％的人口具有如此极高的星云排放，这意味着星系可能会经常在Z $> $ 6处经常发生强烈的星形形成。我们认为，在光子生产效率和逃生部分方面，这种人群可能是电离时代最有效的电离剂之一。我们此外，建议通过这种大型SSFR相的星系在形成结合的星形簇方面非常有效。
We quantify the distribution of [OIII]+H$β$ line strengths at z$\simeq$7 using a sample of 20 bright (M$_{\mathrm{UV}}$ $\lesssim$ $-$21) galaxies. We select these systems over wide-area fields (2.3 deg$^2$ total) using a new colour-selection which precisely selects galaxies at z$\simeq$6.63$-$6.83, a redshift range where blue Spitzer/IRAC [3.6]$-$[4.5] colours unambiguously indicate strong [OIII]$+$H$β$ emission. These 20 galaxies suggest a log-normal [OIII]$+$H$β$ EW distribution with median EW = 759$^{+112}_{-113}$ $\mathrm{\mathring{A}}$ and standard deviation = 0.26$^{+0.06}_{-0.05}$ dex. We find no evidence for strong variation in this EW distribution with UV luminosity. The typical [OIII]+H$β$ EW at z$\simeq$7 implied by our sample is considerably larger than that in massive star forming galaxies at z$\simeq$2, consistent with a shift toward larger average sSFR (4.4 Gyr$^{-1}$) and lower metallicities (0.16 Z$_\odot$). We also find evidence for the emergence of a population with yet more extreme nebular emission ([OIII]+H$β$ EW$>$1200 $\mathrm{\mathring{A}}$) that is rarely seen at lower redshifts. These objects have extremely large sSFR ($>$30 Gyr$^{-1}$), as would be expected for systems undergoing a burst or upturn in star formation. While this may be a short-lived phase, our results suggest that 20% of the z$\simeq$7 population has such extreme nebular emission, implying that galaxies likely undergo intense star formation episodes regularly at z$>$6. We argue that this population may be among the most effective ionizing agents in the reionization era, both in terms of photon production efficiency and escape fraction. We furthermore suggest that galaxies passing through this large sSFR phase are likely to be very efficient in forming bound star clusters.
