The Importance of Dust Distribution in Ionizing-photon Escape: NIRCam and MIRI Imaging of a Lyman Continuum-emitting Galaxy at z ~ 3.8

Abstract

We present deep JWST/NIRCam and MIRI imaging of Ion1, a previously confirmed Lyman Continuum (LyC)-emitting galaxy at $z_{spec}=3.794$. Together with existing HST imaging, these new observations from the JADES program enable a joint analysis of Ion1's LyC, rest-frame UV, stellar, and dust emission with unprecedented detail. We report the first detection of dust emission at rest-frame $\sim 3\mu$m in a high-redshift LyC-emitting galaxy using MIRI/F1500W. Our analysis suggests a porous distribution of dust in Ion1, with regions exhibiting evidence of dust deficit coinciding both with LyC-emitting regions and with the peak of H$\alpha$ emission. Furthermore, multi-band NIRCam imaging reveals a strong FUV-to-optical color gradient, where LyC-emitting regions appear significantly bluer than the rest of Ion1. Spatially resolved SED fitting confirms that this color gradient is primarily driven by spatially varying dust attenuation. Together, these findings suggest that Ion1's LyC emission originates from a compact star-forming complex near its stellar-light centroid, where stellar feedback carves out low HI column density channels, facilitating LyC escape. However, only a fraction of these LyC photons - specifically those along sightlines with minimal HI obscuration - ultimately escape and reach observers. This work underscores the critical role of dust and neutral gas geometry in shaping LyC escape in galaxies at high redshifts. Anisotropic LyC escape may be a common feature in the early Universe, which must be properly incorporated to constrain the Epoch of Reionization.

arXiv commentAccepted for publication in ApJ Letters. 23 pages, 11 figures

References in corpus (86)

• Stellar population synthesis at the resolution of 2003
• Gaia Data Release 2. Summary of the contents and survey properties
• On the variation of the Initial Mass Function
• Star Formation in the Milky Way and Nearby Galaxies
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• EAZY: A Fast, Public Photometric Redshift Code
• Detailed Decomposition of Galaxy Images. II. Beyond Axisymmetric Models
• A Simple Model for the Absorption of Starlight by Dust in Galaxies
• The Great Observatories Origins Deep Survey: Initial Results From Optical and Near-Infrared Imaging
• The propagation of uncertainties in stellar population synthesis modeling III: model calibration, comparison, and evaluation
• Analysis of galaxy SEDs from far-UV to far-IR with CIGALE: Studying a SINGS test sample
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Inferring the star-formation histories of massive quiescent galaxies with BAGPIPES: Evidence for multiple quenching mechanisms
• An updated MILES stellar library and stellar population models
• The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years
• Stellar Population Inference with Prospector
• The Relation Between Optical Extinction and Hydrogen Column Density in the Galaxy
• Identifying Luminous AGN in Deep Surveys: Revised IRAC Selection Criteria
• New Constraints on Cosmic Reionization from the 2012 Hubble Ultra Deep Field Campaign
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• CANDELS Multi-wavelength Catalogs: Source Detection and Photometry in the GOODS-South Field
• The James Webb Space Telescope Mission
• Reionization after Planck: The Derived Growth of the Cosmic Ionizing Emissivity now matches the Growth of the Galaxy UV Luminosity Density
• Nebular Continuum and Line Emission in Stellar Population Synthesis Models
• NIRCam Performance on JWST In Flight
• Escape fraction of ionizing photons during reionization: effects due to supernova feedback and runaway OB stars
• Toward High-Precision Astrometry with WFPC2. I. Deriving an Accurate PSF
• Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• The Main Sequence of star-forming galaxies across cosmic times
• Low-redshift Lyman continuum leaking galaxies with high [OIII]/[OII] ratios
• The Keck Lyman Continuum Spectroscopic Survey (KLCS): The Emergent Ionizing Spectrum of Galaxies at $z\sim 3$
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright, Star-Forming Galaxies with High Escape Fractions
• Lyman continuum leaking from the compact star-forming dwarf galaxy J0925+1403
• Escape of Ionizing Radiation from High Redshift Galaxies
• J1154+2443: a low-redshift compact star-forming galaxy with a 46 per cent leakage of Lyman continuum photons
• Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies
• Galaxy Formation and Reionization: Key Unknowns and Expected Breakthroughs by the James Webb Space Telescope
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of 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%
• An extreme [OIII] emitter at $z=3.2$: a low metallicity Lyman continuum source
• The Lyman Continuum Escape Survey: Ionizing Radiation from [O III]-Strong Sources at a Redshift of 3.1
• Direct Lyman continuum and Lyman-alpha escape observed at redshift 4
• The Low-Redshift Lyman Continuum Survey I: New, Diverse Local Lyman-Continuum Emitters
• Escape of Lyman continuum radiation from local galaxies - Detection of leakage from the young starburst Tol 1247-232
• Deep U band and R imaging of GOODS-South: Observations,data reduction and first results
• Q1549-C25: A Clean Source of Lyman-Continuum Emission at $z=3.15$
• The Low-Redshift Lyman Continuum Survey II: New Insights into LyC Diagnostics
• The Hubble Legacy Field GOODS-S Photometric Catalog
• The Far-Ultraviolet Continuum Slope as a Lyman Continuum Escape Estimator at High-redshift
• The Great Observatories Origins Deep Survey: Constraints on the Lyman Continuum Escape Fraction Distribution of Lyman--Break Galaxies at 3.4<z<4.5
• The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars
• Binary Stars Can Provide the "Missing Photons" Needed for Reionization
• Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph
• On The Detection Of Ionizing Radiation Arising From Star-Forming Galaxies At Redshift z ~ 3-4 : Looking For Analogs Of "Stellar Reionizers"
• JWST NIRCam+NIRSpec: Interstellar medium and stellar populations of young galaxies with rising star formation and evolving gas reservoirs
• Gravitational lensing reveals ionizing ultraviolet photons escaping from a distant galaxy
• The VANDELS ESO public spectroscopic survey
• Understanding the escape of LyC and Ly$\alpha$ photons from turbulent clouds
• The origin of the escape of Lyman alpha and ionizing photons in Lyman Continuum Emitters
• Systematic infrared 2.5-5 micron spectroscopy of nearby ultraluminous infrared galaxies with AKARI
• Galaxy Build-up in the first 1.5 Gyr of Cosmic History: Insights from the Stellar Mass Function at $z\sim 4-9$ from JWST NIRCam Observations
• High star cluster formation efficiency in the strongly lensed Sunburst Lyman-continuum galaxy at z=2.37
• The Low-Redshift Lyman Continuum Survey. Unveiling the ISM properties of low-$z$ Lyman continuum emitters
• The blue UV slopes of z~4 Lyman break galaxies: implications for the corrected star formation rate density
• AGN Selection and Demographics: A New Age with JWST/MIRI
• All the PAHs: an AKARI-Spitzer Cross Archival Spectroscopic Survey of Aromatic Emission in Galaxies
• A new technique for finding galaxies leaking Lyman-continuum radiation: [SII]-deficiency
• Spatial variations in aromatic hydrocarbon emission in a dust-rich galaxy
• HST Imaging of the Ionizing Radiation from a Star-forming Galaxy at z = 3.794
• No strong dependence of Lyman continuum leakage on physical properties of star-forming galaxies at $3.1\lesssim \mathbf{z}\lesssim 3.5$
• UV absorption lines and their potential for tracing the Lyman continuum escape fraction
• Damping Wing-Like Features in the Stacked Ly$\alpha$ Forest: Potential Neutral Hydrogen Islands at $z<6$
• Reconciling escape fractions and observed line emission in Lyman-continuum-leaking galaxies
• Clues on the presence and segregation of very massive stars in the Sunburst Lyman-continuum cluster at z=2.37
• JADES: Primaeval Lyman-$\alpha$ emitting galaxies reveal early sites of reionisation out to redshift $z\sim 9$
• JADES + JEMS: A Detailed Look at the Buildup of Central Stellar Cores and Suppression of Star Formation in Galaxies at Redshifts 3 < z < 4.5
• AGN Selection Methods Have Profound Impacts on the Distributions of Host Galaxy Properties
• A contribution to the selection of emission-line galaxies using narrow-band filters in the optical airglow windows
• The Lyman Continuum Escape Fraction of Star-forming Galaxies at $2.4\lesssim z\lesssim 3.0$ from UVCANDELS
• The Lyman Alpha Reference Sample. XVI. Global 21cm HI properties of Lyman-$\alpha$ emitting galaxies

Cited by in corpus (4)

• The Lyman-alpha and Continuum Origins Survey. I. Survey description and Ly$\alpha$ imaging
• The Lyman-alpha and Continuum Origins Survey II: the connection between the escape of ionizing radiation and Lyman-alpha halos in star-forming galaxies
• The Ly$\alpha$ and Continuum Origins Survey. III. Investigating the Link between Galaxy Morphology, Merger Properties and LyC Escape
• REBELS-IFU: Spatially Resolved Ionizing Photon Production Efficiencies of 12 Bright Galaxies in the Epoch of Reionization