The Magellan M2FS Spectroscopic Survey of High-redshift Galaxies: A Sample of 260 Lyα Emitters at Redshift z ≈ 5.7

Abstract

Abstract We present a spectroscopic survey of Lyα emitters (LAEs) at z ≈ 5.7 using the multiobject spectrograph M2FS on the Magellan Clay telescope. This is part of a high-redshift galaxy survey carried out in several well-studied deep fields. These fields have deep images in multiple UV/optical bands, including a narrow NB816 band that has allowed an efficient selection of LAE candidates at z ≈ 5.7. Our sample consists of 260 LAEs and covers a total effective area of more than 2 deg2 on the sky. This is so far the largest (spectroscopically confirmed) sample of LAEs at this redshift. We use the secure redshifts and narrowband photometry to measure Lyα luminosities. We find that these LAEs span a Lyα luminosity range of erg s−1 and include some of the most luminous galaxies known at in terms of Lyα luminosity. Most of them have rest-frame equivalent widths between 20 and 300 Å, and more luminous Lyα emission lines tend to have broader line widths. We detect a clear offset of ∼20 Å between the observed Lyα wavelength distribution and the NB816 filter transmission curve, which can be explained by the intergalactic medium absorption of continua blueward of Lyα in the high-redshift spectra. This sample is being used to study the Lyα luminosity function and galaxy properties at z ≈ 5.7.