A multi-wavelength study of z = 3.15 Lyman-alpha emitters in the GOODS South Field

TL;DR

This study uses multi-wavelength observations to analyze the properties of z=3.15 Ly-alpha emitters in the GOODS-S field, revealing their low metallicity, low dust content, and similarity to Lyman Break Galaxies, highlighting their role as probes of distant star-forming galaxies.

Contribution

First detailed multi-wavelength analysis of z=3.15 Ly-alpha emitters, comparing their properties with Lyman Break Galaxies and revealing their typical characteristics.

Findings

Emitters have low metallicity and dust extinction.

They are similar to Lyman Break Galaxies but are intrinsically fainter.

Filamentary structures traced by Ly-alpha emitters at 4 sigma significance.

Abstract

Context: Ly-alpha-emitters have proven to be excellent probes of faint, star-forming galaxies in the high redshift universe. However, although the sample of known emitters is increasingly growing, their nature (e.g. stellar masses, ages, metallicities, star-formation rates) is still poorly constrained. Aims: We aim to study the nature of Ly-alpha-emitters, to find the properties of a typical Ly-alpha-emitting galaxy and to compare these properties with the properties of other galaxies at similar redshift, in particular Lyman-break galaxies. Methods: We have performed narrow-band imaging at the VLT, focused on Ly-alpha at redshift z ~ 3.15, in the GOODS-S field. We have identified a sample of Ly-alpha-emitting candidates, and we have studied their Spectral Energy Distributions (SEDs). Results: We find that the emitters are best fit by an SED with low metallicity (Z/Z_sun = 0.005), low dust extinction (A_V ~ 0.32) and medium stellar masses of approximately 10^9 M_sun. The age is not very well constrained. One object out of 24 appears to be a high redshift Ly-alpha-emitting dusty starburst galaxy. We find filamentary structure as traced by the Ly-alpha-emitters at the 4 sigma level. The rest-frame UV SED of these galaxies is very similar to that of Lyman Break Galaxies (LBGs) and comply with the selection criteria for U-band drop-outs, except they are intrinsically fainter than the current limit for LBGs. Conclusion: Ly-alpha-emitters are excellent probes of galaxies in the distant universe, and represent a class of star-forming, dust and AGN free, medium mass objects.