A High-Resolution Hubble Space Telescope Study of Apparent Lyman Continuum Leakers at $z\sim 3$

Abstract

We present $U_{336}{V}_{606}{J}_{125}{H}_{160}$ follow-up $HST$ observations of 16 $z\sim 3$ candidate LyC emitters in the HS1549+1919 field. With these data, we obtain high spatial-resolution photometric redshifts of all sub-arcsecond components of the LyC candidates in order to eliminate foreground contamination and identify robust candidates for leaking LyC emission. Of the 16 candidates, we find one object with a robust LyC detection that is not due to foreground contamination. This object (MD5) resolves into two components; we refer to the LyC-emitting component as MD5b. MD5b has an observed 1500Å to 900Å flux-density ratio of $(F_{UV}/F_{LyC}{)}_{obs}=4.0\pm 2.0$, compatible with predictions from stellar population synthesis models. Assuming minimal IGM absorption, this ratio corresponds to a relative (absolute) escape fraction of $f_{esc,rel}^{MD5b}=75-100$% ($f_{esc,abs}^{MD5b}=14-19$%). The stellar population fit to MD5b indicates an age of $\lesssim 50$Myr, which is in the youngest 10% of the $HST$ sample and the youngest third of typical $z\sim 3$ Lyman break galaxies, and may be a contributing factor to its LyC detection. We obtain a revised, contamination-free estimate for the comoving specific ionizing emissivity at $z=2.85$, indicating (with large uncertainties) that star-forming galaxies provide roughly the same contribution as QSOs to the ionizing background at this redshift. Our results show that foreground contamination prevents ground-based LyC studies from obtaining a full understanding of LyC emission from $z\sim 3$ star-forming galaxies. Future progress in direct LyC searches is contingent upon the elimination of foreground contaminants through high spatial-resolution observations, and upon acquisition of sufficiently deep LyC imaging to probe ionizing radiation in high-redshift galaxies.

31 pages, 5 tables, 19 figures. Accepted to ApJ. Version with full-resolution figures is available at: http://www.astro.ucla.edu/~aes/Mostardi_HST_LyC.pdf

References in corpus (25)

• EAZY: A Fast, Public Photometric Redshift Code
• K-corrections and filter transformations in the ultraviolet, optical, and near infrared
• An Observational Determination of the Bolometric Quasar Luminosity Function
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• The Subaru/XMM-Newton Deep Survey (SXDS). IV. Evolution of Lya Emitters from z=3.1 to 5.7 in the 1 deg^2 Field: Luminosity Functions and AGN
• Multi-Wavelength Constraints on the Cosmic Star Formation History from Spectroscopy: the Rest-Frame UV, H-alpha, and Infrared Luminosity Functions at Redshifts 1.9<z<3.4
• The Effects of Stellar Rotation. II. A Comprehensive Set of Starburst99 Models
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• The Direct Detection of Lyman-Continuum Emission from Star-forming Galaxies at z~3
• Using Lyman-alpha to detect galaxies that leak Lyman continuum
• Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
• A Local Clue to the Reionization of the Universe
• The First Appearance of the Red Sequence of Galaxies in Proto-Clusters at 2<~z<~3
• The Spectroscopic Properties of Lyα-Emitters at z $\approx$ 2.7: Escaping Gas and Photons from Faint Galaxies
• New Constraints on the Lyman Continuum Escape Fraction at z~1.3
• The Physical Nature of Rest-UV Galaxy Morphology During the Peak Epoch of Galaxy Formation
• A Deep Hubble and Keck Search for Definitive Identification of Lyman Continuum Emitters at z~3.1
• Feedback in the local LBG Analog Haro 11 as probed by far-UV and X-ray observations
• Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation
• Identification of the progenitors of rich clusters and member galaxies in rapid formation at z>2
• VIMOS Ultra-Deep Survey (VUDS): Witnessing the Assembly of a Massive Cluster at z~3.3
• High-Redshift QSOs in the SWIRE Survey and the z~3 QSO Luminosity Function
• A proto-cluster at z=2.45
• Lyman continuum galaxies and the escape fraction of Lyman break galaxies

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