The Magellan M2FS Spectroscopic Survey of High-Redshift Galaxies: A Sample of 260 Ly$\alpha$ Emitters at Redshift $z\approx5.7$

TL;DR

This paper presents the largest spectroscopic survey of 260 Ly$ extalpha$ emitters at redshift $z oughly 5.7$, providing valuable data on their luminosities, properties, and implications for high-redshift galaxy evolution.

Contribution

It introduces a new, extensive spectroscopic sample of high-redshift LAEs, enabling detailed analysis of their luminosity function and spectral characteristics.

Findings

LAEs span luminosities of $2\times10^{42}$ to $5\times10^{43}$ erg s$^{-1}$

Most LAEs have rest-frame equivalent widths between 20 and 300 Å

Detected a 20 Å offset in Ly$ extalpha$ wavelength distribution due to IGM absorption

Abstract

We present a spectroscopic survey of Ly$\alpha$ emitters (LAEs) at $z\approx5.7$ using the multi-object 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 $z\approx5.7$. Our sample consists of 260 LAEs and covers a total effective area of more than two square degrees 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 Ly$\alpha$ luminosities. We find that these LAEs span a Ly$\alpha$ luminosity range of $\sim 2\times10^{42} - 5\times10^{43}$ erg s$^{-1}$, and include some of the most luminous galaxies known at $z \ge 5.7$ in terms of Ly$\alpha$ luminosity. Most of them have rest-frame equivalent widths between 20 and 300 \r{A}, and more luminous Ly$\alpha$ emission lines tend to have broader line widths. We detect a clear offset of $\sim20$ \r{A} between the observed Ly$\alpha$ wavelength distribution and the NB816 filter transmission curve, which can be explained by the intergalactic medium absorption of continua blueward of Ly$\alpha$ in the high-redshift spectra. This sample is being used to study the Ly$\alpha$ luminosity function and galaxy properties at $z\approx5.7$.