论文标题
光学上薄的空间分辨Mg II发射映射电离光子的逃脱
Optically-Thin Spatially-Resolved Mg II Emission Maps the Escape of Ionizing Photons
论文作者
论文摘要
早期形成的星系产生了大量的电离光子。这些光子的一部分逃脱了星系中的气体，以振兴整个宇宙。该逃逸部分对于确定宇宙如何进行电程至关重要，但是中性层间介质排除了高红移处的逃生分数的直接测量。逃生部分的间接估计必须描述宇宙的电源如何开发。在这里，我们介绍了来自红移0.36 Galaxy，J1503+3644的谐振MG II 2800 Doublet的新的Keck Cosmic Web成像仪在空间分辨的光谱中，其先前观察到的逃逸分数为6％。 Mg II发射的空间范围与恒星连续体相似，并且每种MG II双线线都由单个高斯人拟合。 MG II是光学薄的。红色和蓝色Mg II发射线双线的内在通量比，$ r = f_ {2796}/f_ {2803} $，由原子物理学设置为两个，但沿视线沿线的mg $^+$ gas会减少$ r $ r $与Mg II ii光学深度成比例的$ R $。结合金属性，$ r $估计中性气柱密度。观察到的$ r $范围从0.8-2.7范围内，这意味着相对逃逸分数的2个空间变化。逃脱J1503+3644的所有电离光子都通过高$ r $的区域。我们结合了MG II的发射和灰尘衰减，以准确估计十个局部Lyman Continum just ud sugy Galaxies的绝对逃逸部分，并建议MG II可以预测在电离时期内的逃逸分数。
Early star-forming galaxies produced copious ionizing photons. A fraction of these photons escaped gas within galaxies to reionize the entire Universe. This escape fraction is crucial for determining how the Universe became reionized, but the neutral intergalactic medium precludes direct measurement of the escape fraction at high-redshifts. Indirect estimates of the escape fraction must describe how the Universe was reionized. Here, we present new Keck Cosmic Web Imager spatially-resolved spectroscopy of the resonant Mg II 2800 doublet from a redshift 0.36 galaxy, J1503+3644, with a previously observed escape fraction of 6%. The Mg II emission has a similar spatial extent as the stellar continuum, and each of the Mg II doublet lines are well-fit by single Gaussians. The Mg II is optically thin. The intrinsic flux ratio of the red and blue Mg II emission line doublet, $R = F_{2796}/F_{2803}$, is set by atomic physics to be two, but Mg$^+$ gas along the line of sight decreases $R$ proportional to the Mg II optical depth. Combined with the metallicity, $R$ estimates the neutral gas column density. The observed $R$ ranges across the galaxy from 0.8-2.7, implying a factor of 2 spatial variation of the relative escape fraction. All of the ionizing photons that escape J1503+3644 pass through regions of high $R$. We combine the Mg II emission and dust attenuation to accurately estimate the absolute escape fractions for ten local Lyman Continuum emitting galaxies and suggest that Mg II can predict escape fraction within the Epoch of Reionization.
