Nature of High Equivalent Width Emitters in the Epoch of Reionization Revealed by JWST Medium-band Imaging

Abstract

Extreme emission line galaxies (EELGs) at high redshifts are considered key contributors to cosmic reionization at $z>6$ due to their higher ionization efficiencies. We have identified 119 H$\beta$ + [OIII] emitters at $z\sim 7$ selected by a flux excess in the medium-band filter F410M in the public James Webb Space Telescope Cycle-1 fields. Our emitters exhibit a wide range in rest-frame H$\beta$ + [OIII] equivalent width (EWs), 420 $<$ EW${}_0$/Å $<$ 6850 (with the median value of $\sim 1700$ Å). Among them, 19 are EW${}_0$ $>$ 3000 Å, which represent extreme populations even in the context of recent findings with JWST. They are characterized by (i) low stellar mass ($\sim 3\times 10^7$ ${\mathrm{M}}_{\odot }$), (ii) blue colors (${\beta }_{\mathrm{UV}}\sim -2.2$), and (iii) low dust attenuation ($A_{\mathrm{V}}\sim 0.1$ mag). We discuss the physical mechanisms responsible for the observed high rest-frame H$\beta$ + [OIII] EWs, including (1) photoionization by AGN, (2) stellar photoionization in the vicinity of HII regions, and (3) radiative shocks powered by outflows either from AGN or massive stars. Notably, we find 13 emitters with spatially offset H$\beta$ + [OIII] emission compared to the UV and stellar components. Given the absence of obvious signatures of actively accreting black holes, these emitters are likely under strong feedback-driven winds from massive stars. Lastly, we report a unique overdensity of EELGs in one of the observed fields. The discovery of such a "star-bursting" overdensity supports the idea that large ionizing bubbles formed around some EEGLs in the early Universe.

References in corpus (75)

• emcee: The MCMC Hammer
• Galactic Stellar and Substellar Initial Mass Function
• Star Formation in Galaxies Along the Hubble Sequence
• Cosmic Star Formation History
• Galaxies on FIRE (Feedback In Realistic Environments): Stellar Feedback Explains Cosmologically Inefficient Star Formation
• UniverseMachine: The Correlation between Galaxy Growth and Dark Matter Halo Assembly from z=0-10
• A Quantitative Comparison of SMC, LMC, and Milky Way UV to NIR Extinction Curves
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• Present-Day Growth of Black Holes and Bulges: the SDSS Perspective
• The SINS survey of z~2 galaxy kinematics: properties of the giant star forming clumps
• A Large Structure of Galaxies At Redshift z~3 and its Cosmological Implications
• Galaxy Zoo Green Peas: Discovery of A Class of Compact Extremely Star-Forming Galaxies
• CEERS Key Paper I: An Early Look into the First 500 Myr of Galaxy Formation with JWST
• Early Evolution of Disk Galaxies : Formation of Bulges in Clumpy Young Galactic Disks
• Resolved Galaxies in the Hubble Ultra Deep Field: Star Formation in Disks at High Redshift
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Toy Models for Galaxy Formation versus Simulations
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright, Star-Forming Galaxies with High Escape Fractions
• Evidence for Ubiquitous, High-EW Nebular Emission in z~7 Galaxies: Towards a Clean Measurement of the Specific Star Formation Rate using a Sample of Bright, Magnified Galaxies
• The Spectral Energy Distributions Of z~8 Galaxies From The IRAC Ultra Deep Fields: Emission Lines, Stellar Masses, And Specific Star Formation Rates At 650 Myr
• On the frequency, intensity and duration of starburst episodes triggered by galaxy interactions and mergers
• Constraints on the assembly and dynamics of galaxies. II. Properties of kiloparsec-scale clumps in rest-frame optical emission of z ~ 2 star-forming galaxies
• Identification and properties of intense star-forming galaxies at redshifts z>10
• Stellar Populations in Ten Clump-Cluster Galaxies of the Ultra Deep Field
• CEERS Epoch 1 NIRCam Imaging: Reduction Methods and Simulations Enabling Early JWST Science Results
• Ly$\alpha$ emission from Green Peas: the role of circumgalactic gas density, covering, and kinematics
• Clumpy Galaxies in CANDELS. I. The Definition of UV Clumps and the Fraction of Clumpy Galaxies at 0.5<z<3
• Green Pea Galaxies and cohorts: Luminous Compact Emission-Line Galaxies in the Sloan Digital Sky Survey
• Z > 7 galaxies with red Spitzer/IRAC [3.6]-[4.5] colors in the full CANDELS data set: the brightest-known galaxies at Z ~ 7-9 and a probable spectroscopic confirmation at Z=7.48
• Very Strong Emission-Line Galaxies in the WISP Survey and Implications for High-Redshift Galaxies
• A JWST/NIRCam Study of Key Contributors to Reionization: The Star-forming and Ionizing Properties of UV-faint $z\sim 7-8$ Galaxies
• On the oxygen and nitrogen chemical abundances and the evolution of the "green pea" galaxies
• Ly$\alpha$ profile, dust, and prediction of Ly$\alpha$ escape fraction in Green Pea Galaxies
• The CANDELS/SHARDS multi-wavelength catalog in GOODS-N: Photometry, Photometric Redshifts, Stellar Masses, Emission line fluxes and Star Formation Rates
• JWST's PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results
• JADES Imaging of GN-z11: Revealing the Morphology and Environment of a Luminous Galaxy 430 Myr After the Big Bang
• Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at z>1
• EIGER II. first spectroscopic characterisation of the young stars and ionised gas associated with strong H$\beta$ and [OIII] line-emission in galaxies at z=5-7 with JWST
• The Far-Ultraviolet Continuum Slope as a Lyman Continuum Escape Estimator at High-redshift
• z~4 Halpha Emitters in GOODS : Tracing the Dominant Mode for Growth of Galaxies
• The Morphological Diversities Among Star-forming Galaxies at High Redshifts in the Great Observatories Origins Deep Survey (GOODS)
• The [OIII]$+$H$\beta$ Equivalent Width Distribution at z$\simeq$7: Implications for the Contribution of Galaxies to Reionization
• Morphologies of ~190,000 Galaxies at z=0-10 Revealed with HST Legacy Data II. Evolution of Clumpy Galaxies
• The GREATS H$\beta$+[OIII] Luminosity Function and Galaxy Properties at $\mathbf{z}\sim 8$: Walking the Way of JWST
• Halpha Equivalent Widths from the 3D-HST survey: evolution with redshift and dependence on stellar mass
• The Global History of Reionisation
• A gravitationally unstable gas disk of a starburst galaxy 12 billion years ago
• RUBIES: a complete census of the bright and red distant Universe with JWST/NIRSpec
• Inferred Hα Flux as a Star-Formation Rate Indicator at z ~ 4-5: Implications for Dust Properties, Burstiness, and the z = 4-8 Star-Formation-Rate Functions
• Diverse properties of Ly-alpha emission in low-redshift compact star-forming galaxies with extremely high [OIII]/[OII] ratios
• Spitzer Constraints on the z=6.56 Galaxy Lensed by Abell 370
• Model-independent constraints on the hydrogen-ionizing emissivity at z>6
• Elevated ionizing photon production efficiency in faint high-equivalent-width Lyman-alpha emitters
• Massive Dead Galaxies at z~2 with HST Grism Spectroscopy I. Star Formation Histories and Metallicity Enrichment
• An extremely metal poor star complex in the reionization era: Approaching Population III stars with JWST
• JADES: Discovery of extremely high equivalent width Lyman-alpha emission from a faint galaxy within an ionized bubble at z=7.3
• MIDIS: Strong (Hb + [OIII]) and Ha emitters at redshift $z\simeq 7-8$ unveiled with JWST/NIRCam and MIRI imaging in the Hubble eXtreme Deep Field (XDF)
• High Equivalent Width of Hα+[N II] Emission in z~8 Lyman-break Galaxies from IRAC 5.8μm Observations: Evidence for Efficient Lyman-continuum Photon production in the Epoch of Re-ionization
• Identification of High-Redshift Galaxy Overdensities in GOODS-N and GOODS-S
• The James Webb Space Telescope North Ecliptic Pole Time-Domain Field -- I: Field Selection of a JWST Community Field for Time-Domain Studies
• Ubiquitous broad-line emission and the relation between ionized gas outflows and Lyman continuum escape in Green Pea galaxies
• PetroFit: A Python Package for Computing Petrosian Radii and Fitting Galaxy Light Profiles
• The [OIII]$\lambda 5007$ equivalent width distribution at z $\sim 2$: The redshift evolution of the extreme emission line galaxies
• Quiescent low-mass galaxies observed by JWST in the Epoch of Reionization
• The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless Spectroscopy
• The Stellar Initial Mass Function at the Epoch of Reionization
• SuperBoRG: Exploration of point sources at $z\sim 8$ in HST parallel fields
• RELICS: Spectroscopy of gravitationally-lensed $z\simeq 2$ reionization-era analogs and implications for CIII] detections at $z>6$
• The Compact UV Size of Green Pea Galaxies As Local Analogs of High-redshift Ly$\alpha$-Emitters
• Dissection of Halpha Emitters : Low-z Analogs of z>4 Star-Forming Galaxies
• Physical properties of extreme emission-line galaxies at $z\sim 4-9$ from the JWST CEERS survey
• ZFOURGE: Extreme 5007$\mathring{A}$ emission may be a common early-lifetime phase for star-forming galaxies at $z>2.5$
• First Light And Reionisation Epoch Simulations (FLARES) XI: [OIII] emitting galaxies at $5<z<10$
• MOSEL survey: JWST reveals major mergers/strong interactions drive the extreme emission lines in the early universe
• MOSEL Survey: Extremely weak outflows in EoR analogues at z=3-4

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