论文标题
用已解决的Lyman Alpha光谱测量重新离子气泡的特性
Measuring the properties of reionised bubbles with resolved Lyman alpha spectra
论文作者
论文摘要
识别和表征重新离子的气泡使我们能够跟踪它们的大小分布，这取决于主要电离源以及回离和星系演变之间的关系。我们证明，频谱解决$ z \ gtrsim6 $ lyman-alpha（ly $α$）排放可以约束重新离子的区域的性能。具体而言，从源到中性区域的距离设置了最小可观察到的$α$速度偏移与系统性的偏移。在LY $α$共振的蓝色侧检测通量，这意味着源位于一个足够多的离子区域中，光子可以在没有明显的共振吸收的情况下逃脱，因此限制了电离气泡中的尺寸和残留的中性分数。我们估计了星系周围区域的范围，该区域在光学上稀薄至蓝色$α$光子（类似于类星体接近区），这是源的电离光子输出和周围气体密度的函数。这个光学上的薄区域通常为$ \ lyssim 0.3 $ pmpc的半径（允许传输通量$ \ gtrsim -250 $ km s $ s $^{ - 1} $），$ \ lyssim 20 $ 20 $％的距离距离中性区域的距离。在概念验证中，我们演示了$ z \ your $ ly $α$ peak的$ z \ y tage cola1-可能位于离子化区域$> 0.7 $ pmpc中，剩余的中性分数$ <10^{ - 5.5} $。要电离其自身的接近区域，我们推断出Cola1具有很高的电离光子逃生分数（$ f _ {\ Mathrm {ensrm {Esc}}> 0.50 $），相对较陡的紫外线（$β<-1.79 $），低线柔软的气体密度（$ \ sim0.5 \ sim0.5 \ sim0.5 \ times $ cosmic she as a a），cosmic nise Asigny是acimic sim a）。
Identifying and characterising reionised bubbles enables us to track both their size distribution, which depends on the primary ionising sources, and the relationship between reionisation and galaxy evolution. We demonstrate that spectrally resolved $z\gtrsim6$ Lyman-alpha (Ly$α$) emission can constrain properties of reionised regions. Specifically, the distant from a source to a neutral region sets the minimum observable Ly$α$ velocity offset from systemic. Detection of flux on the blue side of the Ly$α$ resonance implies the source resides in a large, sufficiently ionised region that photons can escape without significant resonant absorption, and thus constrains both the sizes of and the residual neutral fractions within ionised bubbles. We estimate the extent of the region around galaxies which is optically thin to blue Ly$α$ photons, analogous to quasar proximity zones, as a function of the source's ionising photon output and surrounding gas density. This optically thin region is typically $\lesssim 0.3$ pMpc in radius (allowing transmission of flux $\gtrsim -250$ km s$^{-1}$), $\lesssim 20$% of the distance to the neutral region. In a proof-of-concept, we demonstrate the $z\approx6.6$ galaxy COLA1 -- with a blue Ly$α$ peak -- likely resides in an ionised region $>0.7$ pMpc, with residual neutral fraction $<10^{-5.5}$. To ionise its own proximity zone we infer COLA1 has a high ionising photon escape fraction ($f_{\mathrm{esc}}>0.50$), relatively steep UV slope ($β< -1.79$), and low line-of-sight gas density ($\sim0.5\times$ the cosmic mean), suggesting it is a rare, underdense line-of-sight.
