MOSEL: Strong [OIII] 5007 Å 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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    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 Å and 2.5 < zphot < 4.0. Using Keck/MOSFIRE, we measure 49 redshifts for galaxies brighter than Ks = 25 mag as part of our Multi-Object Spectroscopic Emission Line (MOSEL) survey. Our spectroscopic success rate is ∼53% and z uncertainty is σz = [Δz/(1+z)] = 0.0135. We confirm 31 ELGs at 3< zspec < 3.8, and show that SELGs have spectroscopic rest-frame [O III]5007 Å equivalent widths of 100-500 Å and tend to be lower-mass systems [log(M*/M ) ∼ 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 fgas ⪆ 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 Å 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 Å emission (EWrest > 200 Å) may be an increasingly important source of ionizing UV radiation at z > 3.

    Original languageEnglish
    Article number45
    Pages (from-to)1-13
    Number of pages13
    JournalAstrophysical Journal
    Issue number1
    Publication statusPublished - 21 Jul 2020

    Bibliographical note

    Copyright 2020 The American Astronomical Society. First published in the Astrophysical Journal, 898(1), 45, 2020, published by IOP Publishing. The original publication is available at Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


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