The Wide Field Imager Lyman-Alpha Search (WFILAS) for Galaxies at Redshift ~5.7: I. A Spatially Compact Lyman-alpha Emitting Galaxy at Redshift 5.721

摘要

We report the spectroscopic confirmation of a compact \lya emitting galaxy at$z=5.721$. A FORS2 spectrum of the source shows a strong asymmetric line with aflux of 5$\times10^{-17}$ erg s$^{-1}$ cm$^{-2}$, making it one of thebrightest \lya emitting galaxies at this redshift, and a line-of-sight velocitydispersion of 400 km s$^{-1}$. We also have a tentative detection of a second,narrower component that is redshifted by 400 km s$^{-1}$ with respect to themain peak. A FORS2 image shows that the source is compact, with a FWHM of0\farcs5, which corresponds to 3.2 kpc at this redshift. This source is abrighter example of \object{J1236.8+6215} \citep{Dawson02}, another \lya\emitting galaxy at $z\sim5.2$.