Green peas in the southern sky: Broad-band color selection and spectroscopic follow up

TL;DR

This study systematically identifies Green Pea galaxy candidates from DES DR2, confirms their properties through spectroscopic follow-up, and finds they are low-metallicity, starburst systems at z=0.3-0.41, contributing to understanding early galaxy evolution.

Contribution

First large-scale selection of Green Pea candidates from DES data with spectroscopic confirmation and analysis of their star formation and metallicity properties.

Findings

Candidates exhibit high star formation rates and low metallicity.

Spectroscopic confirmation at z=0.3-0.41 with starburst classification.

Genuine GPs are less chemically evolved than typical star-forming galaxies.

Abstract

We present a systematic search for 1696 Green Pea (GP) galaxy candidates in the southern hemisphere selected from the Dark Energy Survey Data Release 2 (DES DR2) and provide preliminary results from spectroscopic follow-up observations of 26 targets chosen among them. Our selection criteria include the colors in $gri$-bands and compact morphology in the color composite images. The multi-wavelength spectral energy distribution fitting shows that the selected GP candidates exhibit star formation rates up to several tens $\mathrm{M}_\odot\,\mathrm{yr}^{-1}$. With the mean stellar mass of $\mathrm{log}\,M_*/\mathrm{M}_\odot=8.6$, GP candidates are located at roughly 1 dex above the main sequence of star-forming galaxies at $z\sim0.3$. Spectroscopic follow-up observations of the GP candidates with Gemini/GMOS are underway. All 26 targets are spectroscopically confirmed to be at $z=0.3-0.41$ and have [OIII] equivalent width larger than 85$\r{A}$, classified to be starbursts with low to moderate dust attenuation. These confirmed GPs show a lower metallicity offset from the mass-metallicity relation of local star-forming galaxies, indicating that GPs are less chemically evolved systems at their early stage of evolution.