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arXiv 1809.00765astro-ph.GA
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用HST遗留数据揭示的z=0-10时约190,000个镓的形态。III。Lya发射体的连续分布和尺寸演化

Morphologies of ~190,000 Galaxies at z=0-10 Revealed with HST Legacy Data. III. Continuum Profile and Size Evolution of Lya Emitters

Takatoshi Shibuya, Masami Ouchi, Yuichi Harikane, Kimihiko Nakajima

摘要:

本文给出了9119个Lya发射体(LAEs)的静止坐标系UV和光学连续统径向表面亮度(SB)分布在z~0-8和z ~ 0-2处的红移演化。利用Hubble空间望远镜观测数据和文献中的LAE星表,通过拟合得到了9119个LAE和180,000个photo-z恒星形成星系(SFG)和Lyman break星系(LBG)的结构量。从936个拟合良好的LAEs中,我们仔细定义了在z~0-8范围内的UV连续发光度和Lya等效宽度范围内的LAEs的均匀样本,并评估了红移的演化。我们发现,有效半径r_e的分布符合对数正态分布,在z~0-7范围内,LAEs的Sersic指数中值在n~1-1.5之间几乎是常数,表明典型LAEs具有星盘形态。LAEs的大小-光度关系随着SFG和LBG的大小-光度关系向高Z单调减小。LAE的平均r_e值随r_e~(1+z)^-1.37显著演化,与相同光度范围内的SFG和LBG相似,而以前的研究认为LAE样品可能偏向于低z的微弱源,因此认为LAE没有演化。LAEs的r_e分布、恒星形成率面密度和恒星晕尺寸比与SFG和LBG的相似,表明LAEs具有类似SFG和LBG的恒星成分,其Lya发射率受星际/环银河系介质的几何、运动学和电离状态等非恒星物理因素的控制。

英文摘要:

We present the redshift evolution of the radial surface brightness (SB) profile of the rest-frame UV and optical stellar continua for 9119 Lya emitters (LAEs) at z~0-8 and 0-2, respectively. Using Hubble Space Telescope data and the LAE catalogs taken from the literature, we derive the structural quantities of the 9119 LAEs and ~180,000 comparison galaxies of photo-z star-forming galaxies (SFGs) and Lyman break galaxies (LBGs) by the well-tested profile fitting. From 936 well-fitted LAEs, we carefully define the homogeneous sample of LAEs falling in the same ranges of UV-continuum luminosity and Lya equivalent width over z~0-8, and evaluate the redshift evolution. We find that the effective radius r_e distribution is represented by a log-normal function, and that the median Sersic index is almost constant at n~1-1.5 for the LAEs over z~0-7, suggesting that typical LAEs have a stellar-disk morphology. The size-luminosity relation of the LAEs monotonically decreases towards high-z, following size-luminosity relations of SFGs and LBGs. The median r_e values of the LAEs significantly evolve as r_e~(1+z)^-1.37, similar to those of the SFGs and LBGs in the same luminosity range, in contrast with the claims of no evolution made by previous studies whose LAE samples are probably biased to faint sources at low-z. The r_e distribution, star-formation rate surface densities, and stellar-to-halo size ratios of the LAEs are comparable with those of the SFGs and LBGs, indicating that LAEs have stellar components similar to SFGs and LBGs with a Lya emissivity controlled by the non-stellar physics such as geometry, kinematics, and ionization states of the inter-stellar/circum-galactic medium.

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