Abstract
Abstract
We present measurements of [Neiii]λ3869 emission in z ∼ 1 low-mass galaxies taken from the Keck/DEIMOS spectroscopic surveys HALO7D and DEEPwinds. We identify 167 individual galaxies with significant [Neiii] emission lines, including 112 “dwarf” galaxies with
log
(
M
⋆
/
M
⊙
)
<
9.5
, with 0.3 < z < 1.4. We also measure [Neiii] emission from composite spectra derived from all [Oii]λλ3727,3729 line emitters in this range. This provides a unique sample of [Neiii] emitters between well-studied emitters at z = 0 and 2 < z < 3. To study evolution in ionization conditions in the interstellar medium (ISM) over this time, we analyze the log([Neiii]λ3869/[Oii]λλ3727,3729) ratio (Ne3O2) as a function of the stellar mass and of the log([Oiii]λλ4959,5007/[Oii]λλ3727,3729) ratio (O32). We find that the typical star-forming dwarf galaxy at this redshift, as measured from the composite spectra, shares the Ne3O2–M
⋆ relation with local galaxies but has higher O32 at a given Ne3O2. This finding implies that the ionization and metallicity characteristics of the z ∼ 1 dwarf population do not evolve substantially from z ∼ 1 to z = 0, suggesting that the known evolution in those parameters from z ∼ 2 has largely taken place by z ∼ 1. Individual [Neiii]-detected galaxies have emission characteristics situated between local and z ∼ 2 galaxies, with elevated Ne3O2 and O32 emission potentially explained by variations in stellar and nebular metallicity. We also compare our dwarf sample to similarly low-mass z > 7 galaxies identified in JWST Early Release Observations, finding four HALO7D dwarfs with similar size, metallicity, and star formation properties.
Funder
National Aeronautics and Space Administration
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
3 articles.
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