The Neon Gap: Probing Ionization with Dwarf Galaxies at z~1

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_{\star}/M_{\odot}) < 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 in the gap between well-studied emitters at z = 0 and 2 < z < 3. To study evolution in ionization conditions in the 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_{\star} relation with local galaxies, but have higher O32 at 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 parameter 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.

arXiv commentAccepted to ApJL, 16.01.2023

References in corpus (45)

• Star Formation in Galaxies Along the Hubble Sequence
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Cosmic Star Formation History
• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• Theoretical Modeling of Starburst Galaxies
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products and Mosaics
• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• AMAZE. I. The evolution of the mass-metallicity relation at z>3
• The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• The Mass-Metallicity Relation with the Direct Method on Stacked Spectra of SDSS Galaxies
• Understanding Galaxy Evolution through Emission Lines
• The MOSFIRE Deep Evolution Field (MOSDEF) Survey: Rest-Frame Optical Spectroscopy for ~1500 H-Selected Galaxies at 1.37 < z < 3.8
• A Public Ks-selected Catalog in the COSMOS/UltraVISTA Field: Photometry, Photometric Redshifts and Stellar Population Parameters
• Gas metallicity diagnostics in star-forming galaxies
• Stellar Population Effects on the Inferred Photon Density at Reionization
• Direct Oxygen Abundances for Low Luminosity LVL Galaxies
• The Gaseous Environment of High-z Galaxies: Precision Measurements of Neutral Hydrogen in the Circumgalactic Medium of z ~ 2-3 Galaxies in the Keck Baryonic Structure Survey
• The MOSDEF Survey: Electron Density and Ionization Parameter at $z\sim 2.3$
• New calibrations for abundance determinations in HII regions
• Nebular Emission Line Ratios in z~2-3 Star-Forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio
• Deriving model-based T${}_e$-consistent chemical abundances in ionised gaseous nebulae
• Ly$\alpha$ profile, dust, and prediction of Ly$\alpha$ escape fraction in Green Pea Galaxies
• AGN Emission Line Diagnostics and the Mass-Metallicity Relation up to Redshift z~2: the Impact of Selection Effects and Evolution
• The Low-Redshift Lyman Continuum Survey I: New, Diverse Local Lyman-Continuum Emitters
• First look with JWST spectroscopy: $z\sim 8$ galaxies resemble local analogues
• Fast, Slow, Early, Late: Quenching Massive Galaxies at z~0.8
• CHAOS III: Gas-Phase Abundances in NGC5457
• The MOSDEF survey: a stellar mass-SFR-metallicity relation exists at $z\sim 2.3$
• Stochastic modelling of star-formation histories II: star-formation variability from molecular clouds and gas inflow
• Finding Peas in the Early Universe with JWST
• Carbon and oxygen abundance gradients in NGC300 and M33 from optical recombination lines
• [NeIII]/[OII] as an Ionization Parameter Diagnostic in Star-Forming Galaxies
• The MOSDEF Survey: Sulfur Emission-line Ratios Provide New Insights into Evolving ISM Conditions at High Redshift
• Stellar Mass--Gas-phase Metallicity Relation at $0.5\le z\le 0.7$: A Power Law with Increasing Scatter toward the Low-mass Regime
• Assessing the sources of reionisation: a spectroscopic case study of a 30$\times$ lensed galaxy at $z\sim 5$ with Lyα, CIV, MgII, and [NeIII]
• HST Emission Line Galaxies at z ~ 2: The Mystery of Neon
• HALO7D II: The Halo Velocity Ellipsoid and Velocity Anisotropy with Distant Main Sequence Stars
• Disentangling the physical parameters of gaseous nebulae and galaxies
• The MOSDEF Survey: Neon as a Probe of ISM Physical Conditions at High Redshift
• HALO7D I: The Line of Sight Velocities of Distant Main Sequence Stars in the Milky Way Halo
• No evidence for feedback: Unexceptional Low-ionization winds in Host galaxies of Low Luminosity Active Galactic Nuclei at Redshift z ~1
• The Baltimore Oriole's Nest: Cool Winds from the Inner and Outer Parts of a Star-Forming Galaxy at z=1.3
• The Dwarf Galaxy Population at $z\sim 0.7$: A Catalog of Emission Lines and Redshifts from Deep Keck Observations

Cited by in corpus (1)

• Ionized gas metallicity of the strong [OIII]λ emission-line compact galaxies in the LAMOST survey