论文标题
高红移星系中OIII良好结构发射的分析模型
An analytic model for OIII fine structure emission from high redshift galaxies
论文作者
论文摘要
最近的ALMA测量结果表明，在红移时期的电离时期（EOR）期间，星系中明亮的OIII 88微米线发射，高达$ z \ sim 9 $。我们引入了一个分析模型，以帮助解释这些和其他即将进行的OIII 88微米测量。我们的方法总和是从离散的str $ \ ddot {\ mathrm {o}} $ mgren球体中的发射总和，并考虑了给定的星形构型的星系中电离氢的总体积。我们估计双电离氧和电离氢的相对体积及其对电离光子光谱的依赖性。然后，我们计算指定参数的HII区域的不同细胞状态中OIII离子的水平群体。在这个简单的模型中，银河系的OIII 88微米光度由以下确定：HII区域的典型免费电子密度（$ n_e $），这些区域的平均金属性（$ Z $），氢离子化光子的速率（$ q _ {$ q _ {\ MATHRM {hi HI} $）和SHAPLER and Sharge and Sharge and Sharge and Sharge。我们通过将模型与详细的多云计算进行比较，并发现它在广泛的参数空间中的精度高于15 $ \％$的精度。将我们的模型应用于$ z \ sim 6-9 $的现有ALMA数据，我们在这些星系的HII区域的气体密度上得出了较低的界限。这些限制从银河系到星系差异很大，最紧的边界指示$ z \ gtrsim 0.5 z_ \ odot $和$ n _ {\ mathrm {h}} \ Lessim 50 $ cm $^{ - 3} $ at $2-σ$ coluss。
Recent ALMA measurements have revealed bright OIII 88 micron line emission from galaxies during the Epoch of Reionization (EoR) at redshifts as large as $z \sim 9$. We introduce an analytic model to help interpret these and other upcoming OIII 88 micron measurements. Our approach sums over the emission from discrete Str$\ddot{\mathrm{o}}$mgren spheres and considers the total volume of ionized hydrogen in a galaxy of a given star-formation rate. We estimate the relative volume of doubly-ionized oxygen and ionized hydrogen and its dependence on the spectrum of ionizing photons. We then calculate the level populations of OIII ions in different fine-structure states for HII regions of specified parameters. In this simple model, a galaxy's OIII 88 micron luminosity is determined by: the typical number density of free electrons in HII regions ($n_e$), the average metallicity of these regions ($Z$), the rate of hydrogen ionizing photons emitted ($Q_{\mathrm{HI}}$), and the shape of the ionizing spectrum. We cross-check our model by comparing it with detailed CLOUDY calculations, and find that it works to better than 15$\%$ accuracy across a broad range of parameter space. Applying our model to existing ALMA data at $z \sim 6-9$, we derive lower bounds on the gas metallicity and upper bounds on the gas density in the HII regions of these galaxies. These limits vary considerably from galaxy to galaxy, with the tightest bounds indicating $Z \gtrsim 0.5 Z_\odot$ and $n_{\mathrm{H}} \lesssim 50$ cm$^{-3}$ at $2-σ$ confidence.
