Properties of Galaxies in the Reionization Epoch Revealed by the 2012 Hubble Ultra Deep Field Campaign

高红移星系在静止坐标系紫外波长的大小是用2012年哈勃超深场活动获得的深近红外图像测量的，该图像提供了更高的信噪比。分析表明，z~7-10星系的平均半光半径非常小，只有0.3- 0.4kpc，与本地恒星形成星系中的巨分子星协相当。我们还发现，随着红移的增加，半光半径减小的明显趋势在z~8之后继续存在。

The sizes of high-redshift galaxies in the rest-frame ultra-violet wavelengths were measured with deep near-infrared images obtained from the 2012 Hubble Ultra Deep Field campaign, which offered an increased signal-to-noise ratio. The analyses have revealed that the average half-light radii of z~7-10 galaxies are extremely small, 0.3-0.4 kpc, comparable to the sizes of giant molecular associations in local star-forming galaxies. It is also found that the clear trend of decreasing half-light radius with increasing redshift continues beyond z~8.