Elevated ionizing photon production efficiency in faint high-equivalent-width Lyman-alpha emitters

Abstract

While low-luminosity galaxies dominate number counts at all redshifts, their contribution to cosmic Reionization is poorly understood due to a lack of knowledge of their physical properties. We isolate a sample of 35 z~4-5 continuum-faint Lyman-alpha emitters from deep VLT/MUSE spectroscopy and directly measure their Halpha emission using stacked Spitzer/IRAC Ch. 1 photometry. Based on Hubble Space Telescope imaging, we determine that the average UV continuum magnitude is fainter than -16 (~0.01 L_star), implying a median Lyman-alpha equivalent width of 249 Angstroms. By combining the Halpha measurement with the UV magnitude we determine the ionizing photon production efficiency, xi_ion, a first for such faint galaxies. The measurement of log (xi_ion [Hz/erg]) = 26.28 (+0.28; -0.40) is in excess of literature measurements of both continuum- and emission line-selected samples, implying a more efficient production of ionizing photons in these lower-luminosity, Lyman-alpha-selected systems. We conclude that this elevated efficiency can be explained by stellar populations with metallicities between 4e-4 and 0.008, with light-weighted ages less than 3 Myr.

12 Pages, 6 Figures; Accepted for publication in MNRAS

References in corpus (67)

• 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
• An 800-million-solar-mass black hole in a significantly neutral Universe at redshift 7.5
• The MUSE second-generation VLT instrument
• Calibrating Extinction-Free Star Formation Rate Diagnostics with 33GHz Free-Free Emission in NGC6946
• Gusty, gaseous flows of FIRE: galactic winds in cosmological simulations with explicit stellar feedback
• The transition from Population III to normal galaxies: Ly-a and HeII 1640 emission and the ionising properties of high redshift starburst galaxies
• New Constraints on Cosmic Reionization from the 2012 Hubble Ultra Deep Field Campaign
• Understanding Galaxy Evolution through Emission Lines
• Nebular Emission from Star-Forming Galaxies
• An updated analytic model for the attenuation by the intergalactic medium
• Reionization after Planck: The Derived Growth of the Cosmic Ionizing Emissivity now matches the Growth of the Galaxy UV Luminosity Density
• Stellar Population Effects on the Inferred Photon Density at Reionization
• Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated Reionization Around Luminous Star Forming Systems?
• The MUSE Hubble Ultra Deep Field Survey: I. Survey description, data reduction and source detection
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• The HST eXtreme Deep Field XDF: Combining all ACS and WFC3/IR Data on the HUDF Region into the Deepest Field Ever
• 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
• Large Equivalent width Lyman-alpha line emission at z=4.5: young galaxies in a young universe
• 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
• Predicting dust extinction from the stellar mass of a galaxy
• Spectroscopic detection of CIV in a galaxy at z=7.045: Implications for the ionizing spectra of reionization-era galaxies
• Lower-Luminosity Galaxies could reionize the Universe: Very Steep Faint-End Slopes to the UV Luminosity Functions at z>=5-8 from the HUDF09 WFC3/IR Observations
• Ly$\alpha$ emission from Green Peas: the role of circumgalactic gas density, covering, and kinematics
• The z~6 Luminosity Function Fainter than -15 mag from the Hubble Frontier Fields: The Impact of Magnification Uncertainties
• The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to far-infrared catalogs, medium-bandwidth photometric redshifts with improved accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5
• The Extreme Faint End of the UV Luminosity Function at $z\sim 6$ Through Gravitational Telescopes: a comprehensive assessment of strong lensing uncertainties
• 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
• Predicted UV properties of very metal-poor starburst galaxies
• 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
• CANDELS: The Contribution of the Observed Galaxy Population to Cosmic Reionization
• Can the intergalactic medium cause a rapid drop in Lyman alpha emission at z>6?
• The MUSE Hubble Ultra Deep Field Survey: II. Spectroscopic redshifts and comparisons to color selections of high-redshift galaxies
• Stellar Populations of Lyman Alpha Emitters at z~6-7: Constraints on the Escape Fraction of Ionizing Photons from Galaxy Building Blocks
• MMT/MMIRS spectroscopy of $z=1.3-2.4$ extreme [OIII] emitters: Implications for galaxies in the reionization-era
• The Spectroscopic Properties of Lyα-Emitters at z $\approx$ 2.7: Escaping Gas and Photons from Faint Galaxies
• Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at z>1
• The Baryon Cycle of Dwarf Galaxies: Dark, Bursty, Gas-Rich Polluters
• z~4 Halpha Emitters in GOODS : Tracing the Dominant Mode for Growth of Galaxies
• The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization
• The MOSDEF Survey: Direct Observational Constraints on the Ionizing Photon Production Efficiency, ${\xi }_{\mathrm{ion}}$, at z~2
• The production and escape of Lyman-Continuum radiation from star-forming galaxies at z~2 and their redshift evolution
• 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
• The Nature of Extreme Emission Line Galaxies at z=1-2: Kinematics and Metallicities from Near-Infrared Spectroscopy
• New Insights on Ly-alpha and Lyman Continuum Radiative Transfer in the Greenest Peas
• The physics of Lyman-alpha escape from high-redshift galaxies
• The MUSE Hubble Ultra Deep Field Survey VI: The Faint-End of the Lya Luminosity Function at 2.91 < z < 6.64 and Implications for Reionisation
• Ultradeep IRAC Imaging Over The HUDF And GOODS-South: Survey Design And Imaging Data Release
• Physical properties and H-ionizing-photon production rates of extreme nearby star-forming regions
• The Rest-Frame Optical Spectroscopic Properties of Ly$\alpha$-Emitters at $z\sim 2.5$: The Physical Origins of Strong Ly$\alpha$ Emission
• The Major Sources of the Cosmic Reionizing Background at z ~ 6
• Spectroscopic properties of luminous Lyman-α emitters at $z\approx 6-7$ and comparison to the Lyman-break population
• Consequences of bursty star formation on galaxy observables at high redshifts
• The MUSE Hubble Ultra Deep Field Survey X. Ly$\alpha$ Equivalent Widths at $2.9<z<6.6$
• Ly$\alpha$-Lyman Continuum connection in 3.5 < z < 4.3 star-forming galaxies from the VUDS survey
• The Rest Frame UV to Optical Colors and SEDs of z~4-7 Galaxies
• The mean H$\alpha$ EW and Lyman-continuum photon production efficiency for faint $z\approx 4-5$ galaxies
• HDUV: The Hubble Deep UV Legacy Survey
• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
• Confirmation of Small Dynamical and Stellar Masses for Extreme Emission Line Galaxies at z~2
• Mean Halpha+[NII]+[SII] EW Inferred for Star-Forming Galaxies at z=5.1-5.4 Using High-Quality Spitzer/IRAC Photometry
• The role of galaxies and AGN in reionizing the IGM - II: metal-tracing the faint sources of reionization at $5\lesssim z\lesssim 6$
• MUSE Spectroscopic Identifications of Ultra-Faint Emission Line Galaxies with M${}_{\mathrm{UV}}\sim$ -15
• Ly$\alpha$ Emitters with Very Large Ly$\alpha$ Equivalent Widths, EW${}_0$(Ly$\alpha$) $\simeq 200-400$ Å, at $z\sim 2$
• Predicting Lyman-alpha escape fractions with a simple observable: Lyman-alpha in emission as an empirically calibrated star formation rate indicator
• Sub-kiloparsec Imaging of Lyman-alpha Emission in a Low Mass, Highly Ionized, Gravitationally Lensed Galaxy at z = 1.84

Cited by in corpus (47)

• CEERS Spectroscopic Confirmation of NIRCam-Selected z > 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of their Properties
• The Far-Ultraviolet Continuum Slope as a Lyman Continuum Escape Estimator at High-redshift
• JWST/NIRCam Probes Young Star Clusters in the Reionization Era Sunrise Arc
• Astraeus I: The interplay between galaxy formation and reionization
• The MUSE Hubble Ultra Deep Field surveys: Data release II
• New Insights into the Evolution of Massive Stars and Their Effects on Our Understanding of Early Galaxies
• EMPRESS. V. Metallicity Diagnostics of Galaxies over 12+log(O/H)=~6.9-8.9 Established by a Local Galaxy Census: Preparing for JWST Spectroscopy
• JWST unveils heavily obscured (active and passive) sources up to z~13
• JADES: Detecting [OIII]$\lambda 4363$ Emitters and Testing Strong Line Calibrations in the High-$z$ Universe with Ultra-deep JWST/NIRSpec Spectroscopy up to $z\sim 9.5$
• The Star Formation Burstiness and Ionizing Efficiency of Low-mass Galaxies
• The MUSE Deep Lensed Field on the Hubble Frontier Field MACS~J0416
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• Searching for Islands of Reionization: A Potential Ionized Bubble Powered by a Spectroscopic Overdensity at z = 8.7
• The MUSE Extremely Deep Field: the Cosmic Web in Emission at High Redshift
• The Effects of Stellar Population and Gas Covering Fraction on the Emergent Lyman Alpha Emission of High-Redshift Galaxies
• 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
• The ionising photon production efficiency at z~6 for Lyman-alpha emitters using JEMS and MUSE
• Low-redshift compact star-forming galaxies as analogues of high-redshift star-forming galaxies
• Witnessing the onset of reionisation via Lyman-$\alpha$ emission at redshift 13
• An extreme blue nugget, UV-bright starburst at z=3.613 with ninety per cent of Lyman continuum photon escape
• The production of ionizing photons in UV-faint z~3-7 galaxies
• 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
• Equivalent widths of Lyman $\alpha$ emitters in MUSE-Wide and MUSE-Deep
• On the sizes of ionized bubbles around the highest redshift galaxies. Spectral shapes of the Lyman-alpha emission from galaxies
• JADES: Primaeval Lyman-$\alpha$ emitting galaxies reveal early sites of reionisation out to redshift $z\sim 9$
• The MUSE Hubble Ultra Deep Field Survey. XV. The mean rest-UV spectra of Ly-alpha emitters at z>3
• Blue Rest-Frame UV-Optical Colors in z~8 Galaxies from GREATS: Very Young Stellar Populations at ~650 Myr of Cosmic Time
• Properties of five z~0.3-0.4 confirmed LyC leakers: VLT/XShooter observations
• An Hα Impression of Lyα Galaxies at $z\simeq 6$ with Deep JWST/NIRCam Imaging
• Spatially-resolved H$\alpha$ and ionizing photon production efficiency in the lensed galaxy MACS1149-JD1 at a redshift of 9.11
• Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at $1.5<z<6.4$
• The nature of CR7 revealed with MUSE: a young starburst powering extended Lyman-$\alpha$ emission at z=6.6
• Extreme Ionizing Properties of Metal-Poor, Muv ~ -12 Star Complex in the first Gyr
• First Light And Reionisation Epoch Simulations (FLARES) XIII: The Lyman-continuum emission of high-redshift galaxies
• Linking Mg II and [O II] spatial distribution to ionizing photon escape in confirmed LyC leakers and non-leakers
• The evolution of the UV luminosity and stellar mass functions of Lyman-alpha emitters from z~2 to z~6
• Deep Spitzer/IRAC Data for z~10 galaxies Reveal Blue Balmer Break Colors: Young Stellar Populations at ~500 Myr of Cosmic Time
• Deciphering stellar metallicities in the early Universe: Case study of a young galaxy at z = 4.77 in the MUSE eXtremely Deep Field
• The ionizing photon production efficiency of star-forming galaxies at $z\sim 4-10$
• Linking UV spectral properties of MUSE Ly-alpha emitters at z>3 to Lyman continuum escape
• JADES Data Release 4 Paper I: Sample Selection, Observing Strategy and Redshifts of the complete spectroscopic sample
• Spatially resolved H$\alpha$ emission in B14-65666: compact starbursts, ionizing efficiency and gas kinematics in an advanced merger at the Epoch of Reionization
• REBELS-IFU: Spatially Resolved Ionizing Photon Production Efficiencies of 12 Bright Galaxies in the Epoch of Reionization
• Nature of High Equivalent Width Emitters in the Epoch of Reionization Revealed by JWST Medium-band Imaging
• Resolving dust and Lyα emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS
• Extreme equivalent width-selected low-mass starbursts at $z=4-9$: insights into their role in cosmic reionization