Scrutiny of a very young, metal-poor star-forming Lyα-emitter at z ~ 3.7

Abstract

The origin of the Lyman-$\alpha$ (Ly$\alpha$) emission in galaxies is a long-standing issue: despite several processes known to originate this line (e.g. AGN, star formation, cold accretion, shock heating), it is difficult to discriminate among these phenomena based on observations. Recent studies have suggested that the comparison of the ultraviolet (UV) and optical properties of these sources could solve the riddle. For this reason, we investigate the rest-frame UV and optical properties of A2895b, a strongly lensed Ly$\alpha$-emitter at redshift z ~ 3.7. From this study, we find that our target is a compact (r ~ 1.2 pkpc) star-forming (star formation rate ~ 11 M${}_{\odot }$/yr) galaxy having a young stellar population. Interestingly, we measure a high ratio of the H$\beta$ and the UV continuum monochromatic luminosities (L(H$\beta$)/L(UV) ~ 100). Based on tracks of theoretical stellar models (Starburst99, BPASS), we can only partially explain this result by assuming a recent (< 10 Myr), bursty episode of star-formation and considering models characterised by binary stars, a top-heavy initial-mass function (IMF) and sub-solar metallicities (Z < 0.01 Z${}_{\odot }$). These assumptions also explain the observed low (C/O) abundance of our target (~ 0.23(C/O)${}_{\odot }$). By comparing the UV and optical datasets, we find that the Ly$\alpha$ and UV continuum are more extended (x2) than the Balmer lines, and that the peak of the Ly$\alpha$ is offset (~ 0.6 pkpc). The multi-wavelength results of our analysis suggest that the observed Ly$\alpha$ emission originates from a recent star-formation burst, likely taking place in an off-centre clump.

arXiv comment18 pages (including Appendix), 5 figures. Paper accepted for publication on MNRAS. Accepted 2022 November 2. Received 2022 October 22; in original form 2022 August 3

References in corpus (121)

• Star Formation in Galaxies Along the Hubble Sequence
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• How Do Galaxies Get Their Gas?
• Detailed Decomposition of Galaxy Images. II. Beyond Axisymmetric Models
• Galaxy Bimodality due to Cold Flows and Shock Heating
• Galactic Winds
• Dust Absorption And The Ultraviolet Luminosity Density At z \approx 3 As Calibrated By Local Starburst Galaxies
• The 'Forbidden' Abundance of Oxygen in the Sun
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope I. Overview of the instrument and its capabilities
• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• Reevaluating Old Stellar Populations
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• The Ultraviolet Spectrum of MS 1512-cB58: An Insight into Lyman Break Galaxies
• Nebular Continuum and Line Emission in Stellar Population Synthesis Models
• Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies
• SINFONI - Integral Field Spectroscopy at 50 milli-arcsecond resolution with the ESO VLT
• Dust Obscuration and Metallicity at High Redshift: New Inferences from UV, H-alpha, and 8 Micron Observations of z~2 Star-Forming Galaxies
• The MUSE Hubble Ultra Deep Field Survey: I. Survey description, data reduction and source detection
• ZAP -- Enhanced PCA Sky Subtraction for Integral Field Spectroscopy
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths
• Physical Conditions in a Young, Unreddened, Low Metallicity Galaxy at High Redshift
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• The evolution of the dust and gas content in galaxies
• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Infrared Excess of UV-selected z=2-10 galaxies as a function of UV-continuum Slope and Stellar Mass
• On the redshift-evolution of the Lyman-alpha escape fraction and the dust content of galaxies
• Star formation history and dust attenuation in galaxies drawn from ultraviolet surveys
• New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling
• Lyman Alpha Cooling Radiation from High-Redshift Halos
• Very blue UV-continuum slopes of low luminosity z~7 galaxies from WFC3/IR: Evidence for extremely low metallicities?
• A New Diagnostic of Active Galactic Nuclei: Revealing Highly-Absorbed Systems at Redshift>0.3
• The HDUV Survey: A Revised Assessment of the Relationship between UV Slope and Dust Attenuation for High-Redshift Galaxies
• Lyman-alpha Cooling Emission from Galaxy Formation
• Ultraviolet Emission Lines in Young Low Mass Galaxies at z~2: Physical Properties and Implications for Studies at z>7
• 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
• Observations of the Lyman-$\alpha$ Universe
• GOODS-Herschel:dust attenuation properties of UV selected high redshift galaxies
• Lyman Alpha Blobs as an Observational Signature of Cold Accretion Streams into Galaxies
• Direct Lyman continuum and Lyman-alpha escape observed at redshift 4
• Carbon and Oxygen Abundances in Low Metallicity Dwarf Galaxies
• Radio galaxies at z~2.5: results from Keck spectropolarimetry
• Resolved spectroscopy of gravitationally lensed galaxies: global dynamics and star-forming clumps on ~100pc scales
• What is the physical origin of strong Lya emission? II. Gas Kinematics and Distribution of Lya Emitters
• Lyman-alpha emission properties of simulated galaxies: interstellar medium structure and inclination effects
• The Chemical Evolution of Carbon, Nitrogen, and Oxygen in Metal-Poor Dwarf Galaxies
• 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
• A Window On The Earliest Star Formation: Extreme Photoionization Conditions of a High-Ionization, Low-Metallicity Lensed Galaxy at z~2
• Massive star formation in a gravitationally-lensed HII-galaxy at z=3.357
• Average Metallicity and Star Formation Rate of Lya Emitters Probed by a Triple Narrow-Band Survey
• First Spectroscopic Evidence for High Ionization State and Low Oxygen Abundance in Lya Emitters
• A spectroscopic search for AGN activity in the reionization era
• Lyman alpha Resonant Scattering in Young Galaxies - Predictions from Cosmological Simulations
• A Large Reservoir of Ionized Gas in the Galactic Halo: Ionized Silicon in High-Velocity and Intermediate-Velocity Clouds
• Bright and Faint Ends of Ly$\alpha$ Luminosity Functions at $\text{z}=2$ Determined by the Subaru Survey: Implications for AGN, Magnification Bias, and ISM HI Evolution
• High-resolution spectroscopy of a young, low-metallicity optically-thin L=0.02L* star-forming galaxy at z=3.12
• Ionising the Intergalactic Medium by Star Clusters: The first empirical evidence
• Stellar Populations of Lyman Alpha Emitters at z = 3 - 4 Based on Deep Large Area Surveys in the Subaru-SXDS/UKIDSS-UDS Field
• Upgrading electron temperature and electron density diagnostic diagrams of forbidden line emission
• A young star-forming galaxy at z = 3.5 with an extended Ly\,$\alpha$ halo seen with MUSE
• A systematic study of Lyman-Alpha transfer through outflowing shells: Model parameter estimation
• The HETDEX Pilot Survey III: The Low Metallicities of High-Redshift Lyman Alpha Galaxies
• The Recent Burstiness of Star Formation in Galaxies at z~4.5 from H$\alpha$ Measurements
• The Rest Frame Ultraviolet Spectra of UV-Selected Active Galactic Nuclei at z ~ 2-3
• The Rest-Frame Optical Spectroscopic Properties of Ly$\alpha$-Emitters at $z\sim 2.5$: The Physical Origins of Strong Ly$\alpha$ Emission
• The Bursty Star Formation Histories of Low-mass Galaxies at $0.4<z<1$ Revealed by Star Formation Rates Measured from H$\beta$ and FUV
• Ly$\alpha$ Spectra from Multiphase Outflows, and their Connection to Shell Models
• The blue UV slopes of z~4 Lyman break galaxies: implications for the corrected star formation rate density
• Rest-frame ultraviolet spectrum of the gravitationally lensed galaxy `the 8 o'clock arc': stellar and interstellar medium properties
• Deep spectroscopy of the FUV-optical emission lines from a sample of radio galaxies at z~2.5: metallicity and ionization
• Magnifying the early episodes of star formation: super star clusters at cosmological distances
• Probing the faint end of the Galaxy luminosity function at z=3 with Ly-alpha emission
• Properties of z~3-6 Lyman break galaxies. II. Testing star formation histories and the SFR-mass relation with ALMA and near-IR spectroscopy
• MUSE integral-field spectroscopy towards the Frontier Fields Cluster Abell S1063: I. Data products and redshift identifications
• Resolved Spectroscopy of a Gravitationally Lensed L* Lyman-break Galaxy at z~5
• The MUSE Hubble Ultra Deep Field Survey XIII. Spatially resolved spectral properties of Lyman alpha haloes around star-forming galaxies at z > 3
• The Star Formation Burstiness and Ionizing Efficiency of Low-mass Galaxies
• Synthetic nebular emission from massive galaxies II: ultraviolet-line diagnostics of dominant ionizing sources
• Chemical Evolution of High-Redshift Radio Galaxies
• Puzzling Lyman-alpha line profiles in green pea galaxies
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• The Effects of Stellar Population and Gas Covering Fraction on the Emergent Lyman Alpha Emission of High-Redshift Galaxies
• Probing Galaxy Formation with He II Cooling Lines
• An extremely young massive clump forming by gravitational collapse in a primordial galaxy
• Directional Lya equivalent boosting I. Spherically symmetric distributions of clumps
• Evolution of N/O Abundance Ratios and Ionization Parameters from z~0 to 2 Investigated by the Direct Temperature Method
• A High Fraction of Ly-alpha-Emitters Among Galaxies with Extreme Emission Line Ratios at z ~ 2
• HST Emission Line Galaxies at z ~ 2: Comparing Physical Properties of Lyman Alpha and Optical Emission Line Selected Galaxies
• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
• 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?
• What is the Physical Origin of Strong Lya Emission? I. Demographics of Lya Emitter Structures
• Spectral Energy Distribution Fitting of HETDEX Pilot Survey Lyman-alpha Emitters in COSMOS and GOODS-N
• On the Diffuse Lyman-alpha Halo Around Lyman-alpha Emitting Galaxies
• The Kinematics of Extended Lyman-alpha Emission in a Low Mass, Low Metallicity Galaxy at z = 2.3
• Anisotropic Lyman-alpha Emission
• Primordial helium abundance determination using sulphur as metallicity tracer
• Sizes of Lensed Lower-luminosity z=4-8 Galaxies from the Hubble Frontier Field Program
• Lyman Alpha Signatures from Direct Collapse Black Holes
• Spectral variations of Lyman-alpha emission within strongly lensed sources observed with MUSE
• Reconstruction of the ground-layer adaptive-optics point spread function for MUSE Wide Field Mode observations
• Small-scale Intensity Mapping: Extended Ly$\alpha$, H$\alpha$ and Continuum emission as a Probe of Halo Star Formation in High-redshift Galaxies
• Discovery of a faint, star-forming, multiply lensed, Lyman-alpha blob
• Predicting Ly$\alpha$ Emission from Galaxies via Empirical Markers of Production and Escape in the KBSS
• Constraining Lyman-alpha spatial offsets at $3<z<5.5$ from VANDELS slit spectroscopy
• The Dust Attenuation Curve versus Stellar Mass for Emission Line Galaxies at z ~ 2
• A gravitationally-boosted MUSE survey for emission-line galaxies at z>~5 behind the massive cluster RCS 0224
• On the AGN nature of two UV bright sources at z_spec~5.5 in the CANDELS fields: an update of the AGN space density at M1450~-22.5
• Using photo-ionisation models to derive carbon and oxygen gas-phase abundances in the rest UV
• A comparison of UV and optical metallicities in star-forming galaxies
• The Rest-frame Ultraviolet Light Profile Shapes of Ly-alpha-Emitting Galaxies at z=3.1
• Resolving the Stellar Populations in a z=4 Lensed Galaxy
• Multiwavelength analysis of the Lyman alpha emitting galaxy Haro 2: relation between the diffuse Lyman alpha and soft X-ray emissions
• Lyman-Alpha Escape from Low-Mass, Compact, High-Redshift Galaxies
• The HETDEX Survey: The Ly$\alpha$ Escape Fraction from 3D-HST Emission Line Galaxies at $z\sim 2$
• Stellar feedback in a clumpy galaxy at $z\sim$ 3.4
• OV] $\lambda \lambda$1213.8,1218.3 emission from extended nebulae around quasars: contamination of Ly$\alpha$ and a new diagnostic for AGN activity in Ly$\alpha$-emitters
• Resolved galactic superwinds reconstructed around their host galaxies at z>3
• A Peculiar Type~II QSO Identified via Broad-band Detection of Extreme Nebular Line Emission
• Carbon-loud SDSS BOSS QSO2s at z > 2: High density gas or secondary production of Carbon?

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• JADES: The star-formation and chemical enrichment history of a luminous galaxy at z~9.43 probed by ultra-deep JWST/NIRSpec spectroscopy
• DESI Dark Energy Time Evolution is Recovered by Cosmologically Coupled Black Holes
• HeII emitters at cosmic noon and beyond. Characterising the HeII λ1640 emission with MUSE and JWST/NIRSpec
• Constraining the geometry of the gas surrounding a typical galaxy at $z=3.4$ with Ly$\alpha$ polarization