The HDUV Survey: Six Lyman Continuum Emitter Candidates at z~2 Revealed by HST UV Imaging

Abstract

We present six galaxies at z~2 that show evidence of Lyman continuum (LyC) emission based on the newly acquired UV imaging of the Hubble Deep UV legacy survey (HDUV) conducted with the WFC3/UVIS camera on the Hubble Space Telescope (HST). At the redshift of these sources, the HDUV F275W images partially probe the ionizing continuum. By exploiting the HST multi-wavelength data available in the HDUV/GOODS fields, models of the UV spectral energy distributions, and detailed Monte Carlo simulations of the intergalactic medium absorption, we estimate the absolute ionizing photon escape fractions of these galaxies to be very high -- typically >60% (>13% for all sources at 90% likelihood). Our findings are in broad agreement with previous studies that found only a small fraction of galaxies to show high escape fraction. These six galaxies comprise the largest sample yet of LyC leaking candidates at z~2 whose inferred LyC flux has been cleanly observed at HST resolution. While three of our six candidates show evidence of hosting an active galactic nucleus (AGN), two of these are heavily obscured and their LyC emission appears to originate from star-forming regions rather than the central nucleus. This suggests an AGN-aided pathway for LyC escape from these sources. Extensive multi-wavelength data in the GOODS fields, especially the near-IR grism spectra from the 3D-HST survey, enable us to study the candidates in detail and tentatively test some recently proposed indirect methods to probe LyC leakage -- namely, the [OIII]/[OII] line ratio and the H$\beta -$UV slope diagram. High-resolution spectroscopic followup of our candidates will help constrain such indirect methods which are our only hope of studying $f_{esc}$ at z~5-9 in the fast-approaching era of the James Webb Space Telescope.

11 pages, 6 figures, submitted to ApJ

References in corpus (55)

• Planck 2015 results. XIII. Cosmological parameters
• EAZY: A Fast, Public Photometric Redshift Code
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• The MOSFIRE Deep Evolution Field (MOSDEF) Survey: Rest-Frame Optical Spectroscopy for ~1500 H-Selected Galaxies at 1.37 < z < 3.8
• Reionization after Planck: The Derived Growth of the Cosmic Ionizing Emissivity now matches the Growth of the Galaxy UV Luminosity Density
• Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies
• Cosmic Reionization after Planck: Could Quasars Do It All?
• The VIMOS Ultra-Deep Survey: ~10,000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2<z<~6
• Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies
• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• Using Lyman-alpha to detect galaxies that leak Lyman continuum
• Lyman continuum leaking from the compact star-forming dwarf galaxy J0925+1403
• Nebular Emission Line Ratios in z~2-3 Star-Forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio
• A Spectroscopic Survey of Redshift 1.4<z<3.0 Galaxies in the Goods-North Field: Survey Description, Catalogs, and Properties
• Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters
• The BlueTides Simulation: First Galaxies and Reionization
• A Local Clue to the Reionization of the Universe
• Hubble imaging of the ionizing radiation from a star-forming galaxy at z=3.2 with fesc>50%
• AGN Emission Line Diagnostics and the Mass-Metallicity Relation up to Redshift z~2: the Impact of Selection Effects and Evolution
• An extreme [OIII] emitter at $z=3.2$: a low metallicity Lyman continuum source
• UVUDF: Ultraviolet Through Near-infrared Catalog and Photometric Redshifts of Galaxies in the Hubble Ultra Deep Field
• The Spectroscopic Properties of Lyα-Emitters at z $\approx$ 2.7: Escaping Gas and Photons from Faint Galaxies
• Q1549-C25: A Clean Source of Lyman-Continuum Emission at $z=3.15$
• The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization
• Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph
• Cosmic reionization after Planck
• HST-COS Observations of AGN. II. Extended Survey of Ultraviolet Composite Spectra from 159 Active Galactic Nuclei
• The production and escape of Lyman-Continuum radiation from star-forming galaxies at z~2 and their redshift evolution
• The Connection Between Reddening, Gas Covering Fraction, and the Escape of Ionizing Radiation at High Redshift
• The Lyman Alpha Reference Sample: V. The impact of neutral ISM kinematics and geometry on Lyman Alpha escape
• A Deep Hubble and Keck Search for Definitive Identification of Lyman Continuum Emitters at z~3.1
• Spectroscopic Measurements of the Far-Ultraviolet Dust Attenuation Curve at z~3
• A Hard Ionizing Spectrum in z=3-4 Ly-alpha Emitters with Intense [OIII] Emission: Analogs of Galaxies in the Reionization Era?
• The Lyman Continuum escape fraction of galaxies at z=3.3 in the VUDS-LBC/COSMOS field
• Excitation properties of galaxies with the highest [OIII]/[OII] ratios: No evidence for massive escape of ionizing photons
• A High-Resolution Hubble Space Telescope Study of Apparent Lyman Continuum Leakers at $z\sim 3$
• Indirect Evidence for Escaping Ionizing Photons in Local Lyman Break Galaxy Analogs
• Cosmic reionization after Planck II: contribution from quasars
• The UDF05 Follow-up of the HUDF: II. Constraints on Reionization from z-dropout Galaxies
• Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation
• Escape fraction of ionizing photons from galaxies at z=0--6
• Revisiting the Lyman Continuum Escape Crisis: Predictions for z > 6 from Local Galaxies
• The Lyman Continuum Escape Fraction of Low-Mass Star-Forming Galaxies at z~1
• A Comprehensive Comparative Test of Seven Widely-Used Spectral Synthesis Models Against Multi-Band Photometry of Young Massive Star Clusters
• The spectral evolution of the first Galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman continuum leakage
• The Lyman Continuum Escape Fraction of The Cosmic Horseshoe: A Test of Indirect Estimates
• Quantifying Distributions of Lyman Continuum Escape Fraction
• Self-consistent 2-phase AGN torus models: SED library for observers
• Absorption Line Spectroscopy of Gravitationally-Lensed Galaxies: Further Constraints on the Escape Fraction of Ionizing Photons at High Redshift
• Chandra counterparts of CANDELS GOODS-S sources
• Lyman continuum leaking AGN in the SSA22 field
• Reconstructing the redshift evolution of escaped ionizing flux from early galaxies with Planck and HST observations

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• Euclid preparation: IX. EuclidEmulator2 -- Power spectrum emulation with massive neutrinos and self-consistent dark energy perturbations
• Most of the photons that reionized the Universe came from dwarf galaxies
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• Ly$\alpha$-Lyman Continuum connection in 3.5 < z < 4.3 star-forming galaxies from the VUDS survey
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• A Low Lyman Continuum Escape Fraction of $<10\%$ for Extreme [OIII] Emitters in an Overdensity at z$\sim 3.5$
• The Role of Galaxies and AGN in Reionising the IGM - I: Keck Spectroscopy of 5 < z < 7 Galaxies in the QSO Field J1148+5251
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• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
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• Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency
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• Mapping the Escape Fraction of Ionizing Photons Using Resolved Stars: A Much Higher Escape Fraction for NGC 4214
• Lyman Continuum Escape Fraction in Ly$\alpha$ Emitters at $z\simeq 3.1$
• Emission from the circumgalactic medium: from cosmological zoom-in simulations to multiwavelength observables
• Lyman Continuum Escape Fraction from Low-mass Starbursts at z=1.3
• Constraining the Contribution of Galaxies and Active Galactic Nuclei to Cosmic Reionization
• The Lyman Continuum Escape Fraction of Star-forming Galaxies at $2.4\lesssim z\lesssim 3.0$ from UVCANDELS
• Subaru narrow-band imaging search for Lyman continuum from galaxies at z>3 in the GOODS-N field
• z ~ 2.5 - 3 Ionizers in the GOODS-N Field
• Testing an indirect method for identifying galaxies with high levels of Lyman continuum leakage
• The MUSE Extremely Deep Field: Classifying the Spectral Shapes of Lya Emitting Galaxies
• Candidate z ~ 2.5 Lyman Continuum Sources in the GOODS Fields
• High Lyman Continuum Escape Fraction in a Lensed Young Compact Dwarf Galaxy at $z=2.5$