GALEX selected Lyman Break Galaxies at z~2: Comparison with other Populations

TL;DR

This study identifies and analyzes bright Lyman break galaxies at redshift 1.5 to 2.5 using NUV-dropout technique, comparing their properties and selection efficiency with other methods, revealing biases in traditional techniques.

Contribution

It introduces an NUV-dropout method for selecting LBGs at z~2 and compares its effectiveness and biases to existing ground-based color-selection techniques.

Findings

NUV-dropout technique yields higher efficiency in selecting star-forming galaxies.

Approximately 20% of candidates resemble infrared luminous or sub-millimeter galaxies.

Traditional methods bias against massive, red stellar population galaxies.

Abstract

We present results of a search for bright Lyman break galaxies at 1.5<=z<=2.5 in the GOODS-S field using a NUV-dropout technique in combination with color-selection. We derived a sample of 73 LBG candidates. We compare our selection efficiencies to BM/BX- and BzK methods (techniques solely based on ground-based data sets), and find the NUV data to provide greater efficiency for selecting star-forming galaxies. We estimate LBG candidate ages, masses, star formation rates, and extinction from fitting PEGASE synthesis evolution models. We find about 20% of our LBG candidates are comparable to infrared luminous LBGs or sub-millimeter galaxies which are thought to be precursors of massive elliptical galaxies today. Overall, we can show that although BM/BX and BzK methods do identify star-forming galaxies at z~2, the sample they provide biases against those star-forming galaxies which are more massive and contain sizeable red stellar populations. A true Lyman break criterion at z~2 is therefore more directly comparable to the populations found at z~3, which does contain a red fraction.