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arXiv 2104.08282astro-ph.GA
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作为高红移Ly $α$ -发射体局域类似物的紧凑尺寸的绿豌豆半导体

The Compact UV Size of Green Pea Galaxies As Local Analogs of High-redshift Ly$α$-Emitters

Keunho J. Kim, Sangeeta Malhotra, James E. Rhoads, Huan Yang

摘要:

利用40个绿豌豆(GP)星系的样本,研究了Ly $α$从星系逃逸对紫外连续谱大小和光度的依赖性,这些星系是高红移Ly $α$ -发射体(LAEs)的最佳局部类似物.我们利用来自\textit{Hubble Space Telescope}的宇宙起源光谱仪近紫外图像测量具有$0.047''$空间分辨率的紫外尺寸和光度。像大多数星系一样,GP的大小呈对数正态分布。它们还显示出大小和紫外连续发光度之间的正相关性。的大小连续光度关系的GP的斜率是一致的连续选择的恒星形成星系在低和高红移。GP的一个显著特征是非常紧凑的典型半径为0.33 kpc,种群扩散(1 $σ$)为0.19 kpc。在相同的红移值下,GP的大小分布峰值和大小光度关系截距明显小于连续体选择的成星星系。在圆化半光半径($r_{\rm cir,50}$)、Ly $α$等效宽度(EW(Ly $α$))和Ly $α$逃逸分数($f^{Lyα}_{esc}$)之间发现了统计学上显著的反相关性,这表明小的UV连续半径对于Ly $α$发射是至关重要的。一旦适当考虑空间分辨率效应,GP和高红移LAE具有相似的大小。我们的研究结果表明,紧凑/小的尺寸是至关重要的逃逸的Ly $α$光子,和Ly $α$发射体显示恒定的特征尺寸独立于它们的红移。

英文摘要:

We study the dependence of Ly$α$ escape from galaxies on UV continuum size and luminosity using a sample of 40 Green Pea (GP) galaxies, which are the best local analogs of high-redshift Ly$α$-emitters (LAEs). We use the Cosmic Origins Spectrograph near-ultraviolet images from the \textit{Hubble Space Telescope} to measure the UV size and luminosity with $0.047''$ spatial resolution. Like most galaxies the GPs show a log-normal size distribution. They also show a positive correlation between size and UV-continuum luminosity. The slope of the size-continuum luminosity relation for GPs is consistent with those of continuum-selected star-forming galaxies at low and high redshifts. A distinctive feature of GPs is a very compact typical radius of 0.33 kpc with a population spread (1$σ$) of 0.19 kpc. The peak of the size distribution and the intercept of the size-luminosity relation of GPs are noticeably smaller than those of continuum-selected star-forming galaxies at similar redshifts. There are statistically significant anti-correlations found between the circularized half-light radius ($r_{\rm cir,50}$), the Ly$α$ equivalent width (EW(Ly$α$)), and the Ly$α$ escape faction ($f^{Lyα}_{esc}$), suggesting that small UV-continuum radii are crucial for Ly$α$ emission. GPs and high-redshift LAEs have similar sizes, once spatial resolution effects are properly considered. Our results show that a compact/small size is crucial for escape of Ly$α$ photons, and that Ly$α$-emitters show constant characteristic size independent of their redshift.

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