Physical properties of extreme emission-line galaxies at $z\sim 4-9$ from the JWST CEERS survey

Abstract

Extreme emission line galaxies (EELGs) are typically characterized by high equivalent widths (EWs) which are driven by elevated specific star formation rates (sSFR) in low-mass galaxies with subsolar metallicities and little dust. Such extreme systems are rare in the local universe, but the number density of EELGs increases with redshift. Such starburst galaxies are currently presumed to be the main drivers of hydrogen reionization over 5.5<z<15, which serves to motivate many of the searches for high-z EELGs. We aim to characterize the physical properties of a sample of ~730 EELGs at 4<z<9 photometrically selected from the CEERS survey using JWST/NIRCam. We validate our method and demonstrate the main physical properties of a subset of EELGs using NIRSpec spectra. We create synthetic NIRCam observations of EELGs using empirical templates based on ~2000 local metal-poor starbursts to select EELGs based on color-color criteria. We study their properties based on SED fitting and flux excess from emission lines in the photometric filters. Our sample has a mean stellar mass of $10^{7.84}$Msun with high sSFRs with a mean value of $10^{-7.03}$ yr${}^{-1}$. We consider a delayed-$\tau$ model for the star formation history and find our sample of EELGs are young with a mean value of the time after the onset of star formation of 45Myr. We find that they have similar line ratios to local metal-poor starbursts with high log([OIII]/H$\beta$)>0.4-1 which indicates that star formation may be the dominant source of ionization. Based on the photometric fluxes, we find an increase of EW([OIII]+H$\beta$) with sSFR and ${\Sigma }_{SFR}$, and a decrease with age and stellar mass. The sample of EELGs can reach ${\Sigma }_{SFR}>$10Msun yr${}^{-1}$kpc${}^{-2}$ which indicate they are strong candidates of LyC leakers. Another indirect indicator is the high values of O32>5 that can be reached for some galaxies in the sample.

arXiv commentAccepted for publication in A&A. We updated the manuscript following referee's suggestions

References in corpus (73)

• Array Programming with NumPy
• Stellar population synthesis at the resolution of 2003
• The chemical composition of the Sun
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Detailed Structural Decomposition of Galaxy Images
• 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
• The James Webb Space Telescope
• EAZY: A Fast, Public Photometric Redshift Code
• Detailed Decomposition of Galaxy Images. II. Beyond Axisymmetric Models
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Inferring the star-formation histories of massive quiescent galaxies with BAGPIPES: Evidence for multiple quenching mechanisms
• The All-wavelength Extended Groth Strip International Survey (AEGIS) Data Sets
• Galaxy Zoo Green Peas: Discovery of A Class of Compact Extremely Star-Forming Galaxies
• New Constraints on Cosmic Reionization from the 2012 Hubble Ultra Deep Field Campaign
• CEERS Key Paper I: An Early Look into the First 500 Myr of Galaxy Formation with JWST
• The James Webb Space Telescope Mission
• A large Hα survey at z=2.23, 1.47, 0.84 & 0.40: the 11 Gyr evolution of star-forming galaxies from HiZELS
• A CEERS Discovery of an Accreting Supermassive Black Hole 570 Myr after the Big Bang: Identifying a Progenitor of Massive z > 6 Quasars
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• 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
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright, Star-Forming Galaxies with High Escape Fractions
• The MOSDEF Survey: The Evolution of the Mass-Metallicity Relation from $z=0$ to $z\sim 3.3$
• CEERS Epoch 1 NIRCam Imaging: Reduction Methods and Simulations Enabling Early JWST Science Results
• Green Pea Galaxies and cohorts: Luminous Compact Emission-Line Galaxies in the Sloan Digital Sky Survey
• The Mid-Infrared Instrument for JWST, II: Design and Build
• 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
• AGN Emission Line Diagnostics and the Mass-Metallicity Relation up to Redshift z~2: the Impact of Selection Effects and Evolution
• Spectroscopic Confirmation of CEERS NIRCam-selected Galaxies at $\mathbf{z}\simeq 8-10$
• High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9
• MMT/MMIRS spectroscopy of $z=1.3-2.4$ extreme [OIII] emitters: Implications for galaxies in the reionization-era
• The Low-Redshift Lyman Continuum Survey II: New Insights into LyC Diagnostics
• 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 MOSDEF Survey: Optical AGN Diagnostics at z~2.3
• EIGER I. a large sample of [OIII]-emitting galaxies at $5.3<z<6.9$ and direct evidence for local reionization by galaxies
• "Direct" Gas-Phase Metallicity in Local Analogs of High-Redshift Galaxies: Empirical Metallicity Calibrations for High-Redshift Star-Forming Galaxies
• Blueberry galaxies: the lowest mass young starbursts
• Ionized gaseous nebulae chemical abundance determination using the direct method
• The star formation history and metal content of the "Green Peas". New detailed GTC-OSIRIS spectrophotometry of three galaxies
• The Nature of Extreme Emission Line Galaxies at z=1-2: Kinematics and Metallicities from Near-Infrared Spectroscopy
• New Insights into the Evolution of Massive Stars and Their Effects on Our Understanding of Early Galaxies
• Physical properties and H-ionizing-photon production rates of extreme nearby star-forming regions
• Spectral Templates Optimal for Selecting Galaxies at z > 8 with JWST
• Diverse properties of Ly-alpha emission in low-redshift compact star-forming galaxies with extremely high [OIII]/[OII] ratios
• Semi-analytic forecasts for JWST -- IV. Implications for cosmic reionization and LyC escape fraction
• Automatic unsupervised classification of all SDSS/DR7 galaxy spectra
• Extremely Metal-Poor Representatives Explored by the Subaru Survey (EMPRESS). I. A Successful Machine Learning Selection of Metal-Poor Galaxies and the Discovery of a Galaxy with M*<10^6 M_sun and 0.016 Z_sun
• Near-Infrared Spectroscopy of Galaxies During Reionization: Measuring CIII] in a Galaxy at $\mathbf{z}=7.5$
• 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)
• Discovering extremely compact and metal-poor, star-forming dwarf galaxies out to z ~ 0.9 in the VIMOS Ultra-Deep Survey
• The SFR-M${}_{\ast }$ Correlation Extends to Low Mass at High Redshift
• Extreme Emission-Line Galaxies in SDSS. I. Empirical and model-based calibrations of chemical abundances
• Semi-analytic forecasts for JWST -- III. Intrinsic production efficiency of Lyman-continuum radiation
• Discovery of Extreme [OIII]+H$\beta$ Emitting Galaxies Tracing an Overdensity at z~3.5 in CDF-South
• Rest-frame UV spectroscopy of extreme [OIII] emitters at $1.3<z<3.7$: Toward a high-redshift UV reference sample for JWST
• I Zw 18 as morphological paradigm for rapidly assembling high-z galaxies
• Characterization of star-forming dwarf galaxies at 0.1 $\lesssim z\lesssim$ 0.9 in VUDS: Probing the low-mass end of the mass-metallicity relation
• Using [Ne V]/[Ne III] to Understand the Nature of Extreme-Ionization Galaxies
• Ionized gas kinematics and chemical abundances of low-mass star-forming galaxies at $z\sim 3$
• The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless Spectroscopy
• Qualitative interpretation of galaxy spectra
• Broad-band selection, spectroscopic identification, and physical properties of a population of extreme emission line galaxies at 3<z<3.7
• CLEAR: High-Ionization [Ne V] $\lambda$3426 Emission-line Galaxies at $1.4<z<2.3$
• A $Li$ne $Me$asuring library for large and complex spectroscopic data sets: Implementation of a virtual observatory for JWST spectra
• J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe
• ZFOURGE: Extreme 5007$\mathring{A}$ emission may be a common early-lifetime phase for star-forming galaxies at $z>2.5$
• The resolved chemical composition of the starburst dwarf galaxy CGCG007-025: Direct method versus photoionization model fitting
• Bulgeless disks, dark galaxies, inverted color gradients, and other expected phenomena at higher z. The chromatic surface brightness modulation (CMOD) effect
• Multiple emission lines of H$\alpha$ emitters at $z\sim 2.3$ from the broad and medium-band photometry in the ZFOURGE Survey

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