MOSEL: Strong [OIII] 5007 A Emitting Galaxies at (3 < z < 4) from the ZFOURGE Survey

Kim Vy H. Tran, Ben Forrest, Leo Y. Alcorn, Tiantian Yuan, Themiya Nanayakkara, Jonathan Cohn, Michael Cowley, Karl Glazebrook, Anshu Gupta, Glenn G. Kacprzak, Lisa Kewley, Ivo Labbé, Casey Papovich, Lee Spitler, Caroline M.S. Straatman, Adam Tomczak

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    19 Citations (Scopus)

    Abstract

    To understand how strong emission-line galaxies (SELGs) contribute to the overall growth of galaxies and star formation history of the universe, we target SELGs from the ZFOURGE imaging survey that have blended Hβ+[O iii] rest-frame equivalent widths of >230 A and 2.5 < z < 4.0. Using Keck/MOSFIRE, we measure 49 redshifts for galaxies brighter than K s = 25 mag as part of our Multi-Object Spectroscopic Emission Line (MOSEL) survey. Our spectroscopic success rate is ∼53% and z uncertainty is σ z = [Δz/(1+z)] = 0.0135. We confirm 31 ELGs at 3< z < 3.8, and show that SELGs have spectroscopic rest-frame [O iii]5007 A equivalent widths of 100-500 A and tend to be lower-mass systems [ ∼ 8.2-9.6] compared with more typical star-forming galaxies. The SELGs lie ∼0.9 dex above the star-forming main sequence at z ∼ 3.5 and have high inferred gas fractions of f ⪆ 60%, i.e., the inferred gas masses can easily fuel a starburst to double stellar masses within ∼10-100 Myr. Combined with recent results using ZFOURGE, our analysis indicates that (1) strong [O iii]5007 A emission signals an early episode of intense stellar growth in low-mass [M< 0.1,M] galaxies and (2) many, if not most, galaxies at z > 3 go through this starburst phase. If true, low-mass galaxies with strong [O III]5007 A emission (EWrest > 200 A) may be an increasingly important source of ionizing UV radiation at z > 3.

    Original languageEnglish
    Article number45
    JournalAstrophysical Journal
    Volume898
    Issue number1
    DOIs
    Publication statusPublished - 20 Jul 2020

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