The DEEP2 Redshift Survey: Lyman Alpha Emitters in the Spectroscopic Database

TL;DR

This study introduces a novel spectroscopic method for detecting high-redshift Lyman-alpha emitters, confirming its effectiveness by finding consistent number densities and revealing outflow signatures in their spectra.

Contribution

It presents a new spectroscopic search technique for LAEs that complements traditional imaging, demonstrating its capability to identify high-z LAEs and analyze their spectral features.

Findings

Detected nine high-quality LAEs at z=4.4-4.9

Number density aligns with narrowband imaging results

Spectral analysis indicates large-scale outflows in LAEs

Abstract

We present the first results of a search for Lyman-alpha emitters (LAEs) in the DEEP2 spectroscopic database that uses a search technique that is different from but complementary to traditional narrowband imaging surveys. We have visually inspected ~20% of the available DEEP2 spectroscopic data and have found nine high-quality LAEs with clearly asymmetric line profiles and an additional ten objects of lower quality, some of which may also be LAEs. Our survey is most sensitive to LAEs at z=4.4-4.9 and that is indeed where all but one of our high-quality objects are found. We find the number density of our spectroscopically-discovered LAEs to be consistent with those found in narrowband imaging searches. The combined, averaged spectrum of our nine high-quality objects is well fit by a two-component model, with a second, lower-amplitude component redshifted by ~420 km/s with respect to the primary Lyman-alpha line, consistent with large-scale outflows from these objects. We conclude by discussing the advantages and future prospects of blank-sky spectroscopic surveys for high-z LAEs.