Deciphering stellar metallicities in the early Universe: Case study of a young galaxy at z = 4.77 in the MUSE eXtremely Deep Field

Abstract

Directly characterising the first generations of stars in distant galaxies is a key quest of observational cosmology. We present a case study of ID53 at z=4.77, the UV-brightest (but L*) star-forming galaxy at z>3 in the MUSE eXtremely Deep Field with a mass of $10^9$ M${}_{\odot }$. In addition to very strong Lyman-$\alpha$ (Ly$\alpha$) emission, we clearly detect the (stellar) continuum and an NV P-Cygni feature, interstellar absorption, fine-structure emission and nebular CIV emission lines in the 140 hr spectrum. Continuum emission from two spatially resolved components in Hubble Space Telescope data are blended in the MUSE data, but we show that the nebular CIV emission originates from a subcomponent of the galaxy. The UV spectrum can be fit with recent BPASS stellar population models combined with single-burst or continuous star formation histories (SFHs), a standard initial mass function, and an attenuation law. Models with a young age and low metallicity (log10(age/yr)=6.5-7.6 and [Z/H]=-2.15 to -1.15) are preferred. The intrinsic H$\alpha$ luminosity of the best-fit models is an order of magnitude higher than the H$\alpha$ luminosity inferred from Spitzer/IRAC data, which either suggests a high escape fraction of ionising photons, a high relative attenuation of nebular to stellar dust, or a complex SFH. The metallicity appears lower than the metallicity in more massive galaxies at z=3-5, consistent with the scenario according to which younger galaxies have lower metallicities. This chemical immaturity likely facilitates Ly$\alpha$ escape, explaining why the Ly$\alpha$ equivalent width is anti-correlated with stellar metallicity. Finally, we stress that uncertainties in SFHs impose a challenge for future inferences of the stellar metallicity of young galaxies. This highlights the need for joint (spatially resolved) analyses of stellar spectra and photo-ionisation models.

arXiv commentMain results: Figures 3 and 5 show that the observed nebular CIV emission varies spatially within the galaxy and Figure 8 shows the rest-frame UV spectrum is best-fit with very young stellar populations. Accepted for publication in A&A

References in corpus (143)

• The chemical composition of the Sun
• Galactic Stellar and Substellar Initial Mass Function
• Star Formation in Galaxies Along the Hubble Sequence
• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• Mass-loss predictions for O and B stars as a function of metallicity
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• Rest-Frame Ultraviolet Spectra of z~3 Lyman Break Galaxies
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Dust Absorption And The Ultraviolet Luminosity Density At z \approx 3 As Calibrated By Local Starburst Galaxies
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• On the properties of massive Population III stars and metal-free stellar populations
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• Properties and astrophysical implications of the 150 Msun binary black hole merger GW190521
• Reevaluating Old Stellar Populations
• Galaxies and Intergalactic Matter at Redshift z~3: Overview
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• The Birth of a Galaxy: Primordial Metal Enrichment and Stellar Populations
• Keck Spectroscopy of 3<z<7 Faint Lyman Break Galaxies: The Importance of Nebular Emission in Understanding the Specific Star Formation Rate and Stellar Mass Density
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• Nebular Continuum and Line Emission in Stellar Population Synthesis Models
• Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies
• UV-Continuum Slopes of >4000 z~4-8 Galaxies from the HUDF/XDF, HUDF09, ERS, CANDELS-South, and CANDELS-North Fields
• The MUSE Hubble Ultra Deep Field Survey: I. Survey description, data reduction and source detection
• Evidence for PopIII-like stellar populations in the most luminous Lyman-$\alpha$ emitters at the epoch of re-ionisation: spectroscopic confirmation
• Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths
• Metallicity Evolution of Damped Lyman-alpha Systems out to z~5
• Lyman Alpha Radiation From Collapsing Protogalaxies I: Characteristics of the Emergent Spectrum
• The HST eXtreme Deep Field XDF: Combining all ACS and WFC3/IR Data on the HUDF Region into the Deepest Field Ever
• Physical Conditions in a Young, Unreddened, Low Metallicity Galaxy at High Redshift
• Large Equivalent width Lyman-alpha line emission at z=4.5: young galaxies in a young universe
• Stellar masses from the CANDELS survey: the GOODS-South and UDS fields
• Population III stars: hidden or disappeared ?
• Ly$\alpha$ emission from Green Peas: the role of circumgalactic gas density, covering, and kinematics
• New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling
• The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of HeII 1640 in young star clusters
• The FMOS-COSMOS survey of star-forming galaxies at z ~ 1.6. I. Hα-based star formation rates and dust extinction
• Very blue UV-continuum slopes of low luminosity z~7 galaxies from WFC3/IR: Evidence for extremely low metallicities?
• Ultraviolet Emission Lines in Young Low Mass Galaxies at z~2: Physical Properties and Implications for Studies at z>7
• Predicted UV properties of very metal-poor starburst galaxies
• The Star Formation Main Sequence in the Hubble Space Telescope Frontier Fields
• The Lyman-Continuum Photon Production Efficiency xi_{ion} of z~4-5 Galaxies from IRAC-based Halpha Measurements: Implications for the Escape Fraction and Cosmic Reionization
• Ly$\alpha$ profile, dust, and prediction of Ly$\alpha$ escape fraction in Green Pea Galaxies
• The Detectability of the First Stars and Their Cluster Enrichment Signatures
• Ultraviolet spectra of extreme nearby star-forming regions --- approaching a local reference sample for JWST
• Direct Lyman continuum and Lyman-alpha escape observed at redshift 4
• The MOSDEF Survey: Direct-Method Metallicities and ISM Conditions at $z\sim 1.5-3.5$
• UVUDF: Ultraviolet Through Near-infrared Catalog and Photometric Redshifts of Galaxies in the Hubble Ultra Deep Field
• The Constant Average Relationship between Dust-obscured Star Formation and Stellar Mass from $z=0$ to $z=2.5$
• Carbon and Oxygen Abundances in Low Metallicity Dwarf Galaxies
• z~4 Halpha Emitters in GOODS : Tracing the Dominant Mode for Growth of Galaxies
• Kiloparsec-scale gaseous clumps and star formation at $z=5-7$
• Low-metallicity massive single stars with rotation. Evolutionary models applicable to I Zwicky 18
• Simple Models of Metal-Line Absorption and Emission from Cool Gas Outflows
• The VIMOS Ultra Deep Survey: Nature, ISM properties, and ionizing spectra of CIII]1909 emitters at z=2-4
• Detection of dark galaxies and circum-galactic filaments fluorescently illuminated by a quasar at z=2.4
• Spectral Modelling of Star-Forming Regions in the Ultraviolet: Stellar Metallicity Diagnostics for High Redshift Galaxies
• Constraining the metallicities, ages, star formation histories, and ionizing continua of extragalactic massive star populations
• Constraints on the production and escape of ionizing radiation from the emission-line spectra of metal-poor star-forming galaxies
• A Window On The Earliest Star Formation: Extreme Photoionization Conditions of a High-Ionization, Low-Metallicity Lensed Galaxy at z~2
• Measuring the Physical Conditions in High-Redshift Star-Forming Galaxies: Insights from KBSS-MOSFIRE
• The GREATS H$\beta$+[OIII] Luminosity Function and Galaxy Properties at $\mathbf{z}\sim 8$: Walking the Way of JWST
• X-ray binaries as the origin of nebular HeII emission in low-metallicity star-forming galaxies
• SILVERRUSH. V. Census of Lya, [OIII]5007, Ha, and [CII]158um Line Emission with ~1000 LAEs at z=4.9-7.0 Revealed with Subaru/HSC
• Massive star formation in a gravitationally-lensed HII-galaxy at z=3.357
• Slicing COSMOS with SC4K: the evolution of typical Lya emitters and the Lya escape fraction from z~2 to z~6
• The Effects of Stellar Rotation. I. Impact on the Ionizing Spectra and Integrated Properties of Stellar Populations
• The Hawk-I UDS and GOODS Survey (HUGS): Survey design and deep K-band number counts
• The origin of scatter in the star formation rate - stellar mass relation
• The MOSDEF Survey: the Variation of the Dust Attenuation Curve with Metallicity
• The VANDELS survey: the stellar metallicities of star-forming galaxies at 2.5 < z < 5.0
• Stellar Absorption Line Analysis of Local Star-Forming Galaxies: The Relation Between Stellar Mass, Metallicity, Dust Attenuation and Star Formation Rate
• Equilibrium and Sudden Events in Chemical Evolution
• Transition of the initial mass function in the metal-poor environments
• On the Detectability of Lyman-alpha Emission in Star-forming Galaxies: The Role of Dust
• An Ultraviolet Spectroscopic Atlas of Local Starbursts and Star-Forming Galaxies: The Legacy of FOS and GHRS
• The influence of the distribution of cosmic star formation at different metallicities on the properties of merging double compact objects
• Ultraviolet Line Spectra of Metal-Poor Star-Forming Galaxies
• Spectroscopic Measurements of the Far-Ultraviolet Dust Attenuation Curve at z~3
• A young star-forming galaxy at z = 3.5 with an extended Ly\,$\alpha$ halo seen with MUSE
• ALMA reveals metals yet no dust within multiple components in CR7
• Probing the First Stars with Hydrogen and Helium Recombination Emission
• The effect of dust geometry on the Lyman-alpha output of galaxies
• The impact of stars stripped in binaries on the integrated spectra of stellar populations
• Characterizing Extreme Emission Line Galaxies I: A Four-Zone Ionization Model for Very-High-Ionization Emission
• The extended HeII4686-emitting region in IZw18 unveiled: clues for peculiar ionizing sources
• The Rest Frame Ultraviolet Spectra of UV-Selected Active Galactic Nuclei at z ~ 2-3
• When did Population III star formation end?
• Ultradeep IRAC Imaging Over The HUDF And GOODS-South: Survey Design And Imaging Data Release
• Stellar metallicity of star-forming galaxies at z ~ 3
• The Rest-Frame Optical Spectroscopic Properties of Ly$\alpha$-Emitters at $z\sim 2.5$: The Physical Origins of Strong Ly$\alpha$ Emission
• Late Pop III Star Formation During the Epoch of Reionization: Results from the Renaissance Simulations
• Lyman alpha Emitting Galaxies in the Nearby Universe
• The nature of luminous Lyman-alpha emitters at z~2-3: maximal dust-poor starbursts and highly ionising AGN
• The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star Clusters
• A kiloparsec view of a typical star-forming galaxy when the Universe was ~1 Gyr old. Part I. Outflow, halo, and interstellar medium properties
• The MOSDEF Survey: The First Direct Measurements of the Nebular Dust Attenuation Curve at High Redshift
• Linking Ly-alpha and Low-Ionization Transitions at Low Optical Depth
• Dust Attenuation, Star Formation, and Metallicity in z ~ 2-3 Galaxies from KBSS-MOSFIRE
• Intense CIV and HeII Emission in z~0 Galaxies: Probing High-Energy Ionizing Photons
• HeII emitters in the VIMOS VLT Deep Survey: PopIII star formation or peculiar stellar populations in galaxies at 2<z<4.6?
• The Mean Ultraviolet Spectrum of a Representative Sample of Faint z~3 Lyman Alpha Emitters
• The properties of He II 1640 emitters at z ~ 2.5-5 from the VANDELS survey
• Extremely metal-poor galaxies with HST/COS: laboratories for models of low-metallicity massive stars and high-redshift galaxies
• The MUSE Hubble Ultra Deep Field Survey X. Ly$\alpha$ Equivalent Widths at $2.9<z<6.6$
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• The MUSE Extremely Deep Field: the Cosmic Web in Emission at High Redshift
• Elevated ionizing photon production efficiency in faint high-equivalent-width Lyman-alpha emitters
• High-mass X-ray binaries in nearby metal-poor galaxies: on the contribution to nebular HeII emission
• Modelling ultraviolet-line diagnostics of stars, the ionized and the neutral interstellar medium in star-forming galaxies
• The MUSE-Wide Survey: A determination of the Lyman $\alpha$ emitter luminosity function at $3<z<6$
• The spectral evolution of the first Galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman continuum leakage
• A Comprehensive Study of Ly$\alpha$ Emission in the High-redshift Galaxy Population
• The MOSDEF-LRIS Survey: The Connection Between Massive Stars and Ionized Gas in Individual Galaxies at $z\sim 2$
• Initial Mass Function Variations Cannot Explain the Ionizing Spectrum of Low Metallicity Starbursts
• UV Spectral-Slopes at $z=6-9$ in the Hubble Frontier Fields: Lack of Evidence for Unusual or Pop III Stellar Populations
• Modeling $237$ Lyman-$\alpha$ spectra of the MUSE-Wide survey
• A Ly-alpha Emitter with an Extremely Large Rest-frame Equivalent Width of ~900A at z=6.5: A Candidate of Population III-dominated Galaxy?
• Stellar and nebular diagnostics in the UV for star-forming galaxies
• On the nature and physical conditions of the luminous Lya emitter CR7 and its rest-frame UV components
• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
• The VANDELS survey: the relation between UV continuum slope and stellar metallicity in star-forming galaxies at z~3
• Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of Very Massive Stars
• UV absorption lines and their potential for tracing the Lyman continuum escape fraction
• The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMS
• Ultraviolet spectra of extreme nearby star-forming regions: evidence for an overabundance of very massive stars
• The Ultimately Large Telescope -- what kind of facility do we need to detect Population III stars?
• Dark Galaxy Candidates at Redshift ~3.5 Detected with MUSE
• Ly-alpha emitters in the GOODS-S field: a powerful pure nebular SED with N IV] emission at z=5.563
• Mapping the core of the Tarantula Nebula with VLT-MUSE: I. Spectral and nebular content around R136
• The MUSE Hubble Ultra Deep Field Survey. XV. The mean rest-UV spectra of Ly-alpha emitters at z>3
• Stars and gas in the most metal-poor galaxies I: COS and MUSE observations of SBS 0335-052E
• The VANDELS survey: A strong correlation between Ly$\alpha$ equivalent width and stellar metallicity at $3\le \mathbf{z}\le 5$
• Probing Population III Stars in Galaxy IOK-1 at z = 6.96 through He II Emission
• What is the Maximum Mass of a Population III Galaxy?
• On the reliability of CIV 1549 as an abundance indicator for high redshift star-forming galaxies
• Rest-frame UV Properties of Luminous Strong Gravitationally Lensed Ly$\alpha$ Emitters from the BELLS GALLERY Survey
• Early galaxy growth: mergers or gravitational instability?
• The nature of CR7 revealed with MUSE: a young starburst powering extended Lyman-$\alpha$ emission at z=6.6
• Stellar populations and physical properties of starbursts in the Antennae galaxy from self-consistent modelling of MUSE spectra
• Constraining Very High Mass Population III Stars through He II Emission in Galaxy BDF-521 at z = 7.01
• A Peculiar Type~II QSO Identified via Broad-band Detection of Extreme Nebular Line Emission
• Fluorescent C II* 1335A emission spectroscopically resolved in a galaxy at z = 5.754
• Spectroscopy of an extreme [OIII] emitting active galactic nucleus at $z=3.212$: implications for the reionisation era

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• Strong C IV emission from star-forming galaxies: a case for high Lyman continuum photon escape
• Direct Constraints on the Extremely Metal-Poor Massive Stars Underlying Nebular C IV Emission from Ultra-Deep HST/COS Ultraviolet Spectroscopy
• Trading oxygen for iron I: the [O/Fe] -- specific star formation rate relation of galaxies
• UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
• The ALPINE-ALMA [CII] survey: double stellar population and AGN activity in a galaxy at $z\sim 5.5$
• Accelerating Galaxy Winds During the Big Bang of Starbursts
• Probing patchy reionisation with JWST: IGM opacity constraints from the Lyman-$\alpha$ forest of galaxies in legacy extragalactic fields
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