论文标题
在微弱的高等分宽度lyman-alpha发射器中，电离光子生产效率提高
Elevated ionizing photon production efficiency in faint high-equivalent-width Lyman-alpha emitters
论文作者
论文摘要
尽管低亮度星系在所有红移中都占主导地位，但由于缺乏对物理特性的了解，它们对宇宙电离的贡献很少。我们将35 Z〜4-5连续的Lyman-Alpha发射器的样品与深VLT/Muse Spectroscopicy分离，并使用堆叠的Spitzer/IRAC CH直接测量其Halpha排放。 1光度法。基于哈勃空间望远镜成像，我们确定平均紫外线连续体幅度比-16（〜0.01 l_star）淡出，这意味着中间的lyman -alpha等效宽度为249埃词素。通过将HALPHA测量与紫外线幅度相结合，我们确定了电离光子生产效率XI_ION，这是这种微弱星系的第一个。 log（xi_ion [hz/erg]）的测量值= 26.28（+0.28; -0.40）超出了连续和排放线选择样品的文献测量，这意味着这些较低的lumininessy lyman-alpha-alpha-alpha selecretecter systems在这些较低的lumininity中的电离光子产生更有效。我们得出的结论是，这种升高的效率可以用4e-4至0.008之间的金属质量的恒星种群来解释，而轻度加权年龄小于3 MYR。
While low-luminosity galaxies dominate number counts at all redshifts, their contribution to cosmic Reionization is poorly understood due to a lack of knowledge of their physical properties. We isolate a sample of 35 z~4-5 continuum-faint Lyman-alpha emitters from deep VLT/MUSE spectroscopy and directly measure their Halpha emission using stacked Spitzer/IRAC Ch. 1 photometry. Based on Hubble Space Telescope imaging, we determine that the average UV continuum magnitude is fainter than -16 (~0.01 L_star), implying a median Lyman-alpha equivalent width of 249 Angstroms. By combining the Halpha measurement with the UV magnitude we determine the ionizing photon production efficiency, xi_ion, a first for such faint galaxies. The measurement of log (xi_ion [Hz/erg]) = 26.28 (+0.28; -0.40) is in excess of literature measurements of both continuum- and emission line-selected samples, implying a more efficient production of ionizing photons in these lower-luminosity, Lyman-alpha-selected systems. We conclude that this elevated efficiency can be explained by stellar populations with metallicities between 4e-4 and 0.008, with light-weighted ages less than 3 Myr.
