Evidence for Large-Scale Fluctuations in the Metagalactic Ionizing Background Near Redshift Six

Abstract

The observed scatter in intergalactic Lyman-$\alpha$ opacity at $z\lesssim 6$ requires large-scale fluctuations in the neutral fraction of the intergalactic medium (IGM) after the expected end of reionization. Post-reionization models that explain this scatter invoke fluctuations in either the ionizing ultraviolet background (UVB) or IGM temperature. These models make very different predictions, however, for the relationship between Lyman-$\alpha$ opacity and local density. Here we test these models using Lyman-$\alpha$ emitting galaxies (LAEs) to trace the density field surrounding the longest and most opaque known Lyman-$\alpha$ trough at $z<6$. Using deep Subaru Hyper Suprime-Cam narrow-band imaging, we find a highly significant deficit of $z\simeq 5.7$ LAEs within 20 Mpc/$h$ of the trough. The results are consistent with a model in which the scatter in Lyman-$\alpha$ opacity near $z\sim 6$ is driven by large-scale UVB fluctuations, and disfavor a scenario in which the scatter is primarily driven by variations in IGM temperature. UVB fluctuations at this epoch present a boundary condition for reionization models, and may help shed light on the nature of the ionizing sources.

arXiv comment13 pages, 9 figure, submitted to ApJ, comments welcome

References in corpus (54)

• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• The Second Data Release of the Sloan Digital Sky Survey
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Statistics of 207 Lya Emitters at a Redshift Near 7: Constraints on Reionization and Galaxy Formation Models
• 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
• The Hyper Suprime-Cam Software Pipeline
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• UV-Continuum Slopes of >4000 z~4-8 Galaxies from the HUDF/XDF, HUDF09, ERS, CANDELS-South, and CANDELS-North Fields
• The Universe is Reionizing at z~7: Bayesian Inference of the IGM Neutral Fraction Using Ly$\alpha$ Emission from Galaxies
• Detection of Extended He II Reionization in the Temperature Evolution of the Intergalactic Medium
• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• New observations of z~7 galaxies: evidence for a patchy reionization
• The first ultraviolet quasar stacked spectrum at z=2.4 from WFC3
• Systematic Identification of LAEs for Visible Exploration and Reionization Research Using Subaru HSC (SILVERRUSH). I. Program Strategy and Clustering Properties of ~2,000 Lya Emitters at z=6-7 over the 0.3-0.5 Gpc${}^2$ Survey Area
• Great Optically Luminous Dropout Research Using Subaru HSC (GOLDRUSH). I. UV Luminosity Functions at $z\sim 4-7$ Derived with the Half-Million Dropouts on the 100 deg${}^2$ Sky
• Can the intergalactic medium cause a rapid drop in Lyman alpha emission at z>6?
• The Giant Gemini GMOS survey of z>4.4 quasars - I. Measuring the mean free path across cosmic time
• New constraints on Lyman-α opacity with a sample of 62 quasars at z > 5.7
• A Lower Bound on the Cosmic Baryon Density
• The changing Lya optical depth in the range 6<z<9 from MOSFIRE spectroscopy of Y-dropouts
• Rapid Decline of Lyman-alpha Emission Toward the Reionization Era
• Stellar Populations of Lyman Alpha Emitters at z~6-7: Constraints on the Escape Fraction of Ionizing Photons from Galaxy Building Blocks
• No evidence for a significant AGN contribution to cosmic hydrogen reionization
• The lack of intense Lyman~alpha in ultradeep spectra of z=7 candidates in GOODS-S: imprint of reionization?
• Large Fluctuations in the High-Redshift Metagalactic Ionizing Background
• Large fluctuations in the hydrogen-ionizing background and mean free path following the epoch of reionization
• SILVERRUSH. III. Deep Optical and Near-Infrared Spectroscopy for Lya and UV-Nebular Lines of Bright Lya Emitters at z=6-7
• Constraints on X-ray Emissions from the Reionization Era
• Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest
• Early and Extended Helium Reionization Over More Than 600 Million Years of Cosmic Time
• On the rapid demise of Lyman-alpha emitters at z>7 due to the increasing incidence of optically thick absorption systems
• Large scale opacity fluctuations in the Lyman alpha forest: evidence for QSOs dominating the ionising UV background at z ~ 5.5-6 ?
• Large Opacity Variations in the High-Redshift Lyman-alpha Forest: the Signature of Relic Temperature Fluctuations from Patchy Reionization
• The End of Helium Reionization at z~2.7 Inferred from Cosmic Variance in HST/COS HeII Lyman Alpha Absorption Spectra
• The Faint End of the z=5 Quasar Luminosity Function from the CFHTLS
• Models of the Thermal Evolution of the Intergalactic Medium After Reionization
• On the Contribution of Active Galactic Nuclei to the High-Redshift Metagalactic Ionizing Background
• Shadow of a Colossus: A z=2.45 Galaxy Protocluster Detected in 3D Ly-a Forest Tomographic Mapping of the COSMOS Field
• MApping the Most Massive Overdensities Through Hydrogen (MAMMOTH) I: Methodology
• Physical Properties of Spectroscopically-Confirmed Galaxies at z >= 6. I. Basic Characteristics of the Rest-Frame UV Continuum and Lyman-alpha emission
• Have We Detected Patchy Reionization in Quasar Spectra?
• Spatial fluctuations of the intergalactic temperature-density relation after hydrogen reionization
• An Empirical Study of the Relationship between Lyα and UV selected Galaxies: Do Theorists and Observers `Select' the Same Objects?
• Lyman-alpha emitters gone missing: the different evolution of the bright and faint populations
• Large Scale Environment of a $z=6.61$ Luminous Quasar Probed by Ly$\alpha$ Emitters and Lyman Break Galaxies
• SILVERRUSH. II. First Catalogs and Properties of ~2,000 Lya Emitters and Blobs at z~6-7 Identified over the 14-21 deg2 Sky
• The VLT LBG Redshift Survey - V. Characterising the z = 3.1 Lyman Alpha Emitter Population
• Determining the Nature of Late Gunn-Peterson Troughs with Galaxy Surveys
• On the decreasing fraction of Strong Ly$\alpha$ Emitters around $z$ $\sim$ $6$-$7$
• A self-consistent 3D model of fluctuations in the helium-ionizing background
• Large-scale environment of z~5.7 CIV absorption systems I: projected distribution of galaxies
• Quasars as Probes of Late Reionization and Early Structure Formation

Cited by in corpus (62)

• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Large Lyman-alpha opacity fluctuations and low CMB tau in models of late reionization with large islands of neutral hydrogen extending to z<5.5
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Evolution of the AGN UV luminosity function from redshift 7.5
• Long troughs in the Lyman-$\alpha$ forest below redshift 6 due to islands of neutral hydrogen
• The mean free path of ionizing photons at 5 < z < 6: evidence for rapid evolution near reionization
• EIGER I. a large sample of [OIII]-emitting galaxies at $5.3<z<6.9$ and direct evidence for local reionization by galaxies
• Measurements of the z ~ 6 Intergalactic Medium Optical Depth and Transmission Spikes Using a New z > 6.3 Quasar Sample
• Reionization and galaxy inference from the high-redshift Lyα forest
• Observing the tail of reionization: neutral islands in the $z=5.5$ Lyman-$\alpha$ Forest
• Lyman Radiation Hydrodynamics of Turbulent H II Regions in Molecular Clouds: A Physical Origin of LyC Leakage and the Associated Ly$\alpha$ Spectra
• Long Dark Gaps in the Ly$\beta$ Forest at $z<6$: Evidence of Ultra Late Reionization from XQR-30 Spectra
• Chasing the Tail of Cosmic Reionization with Dark Gap Statistics in the Ly$\alpha$ Forest over $5<z<6$
• The Lyman-$\alpha$ forest as a diagnostic of the nature of the dark matter
• Heating of the Intergalactic Medium by Hydrogen Reionization
• Inferring the IGM Neutral Fraction at z ~ 6-8 with Low-Luminosity Lyman Break Galaxies
• Three Lyman-alpha emitting galaxies within a quasar proximity zone at z=5.8
• A comparison of quasar emission reconstruction techniques for $z\ge 5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission
• Damping Wing-Like Features in the Stacked Ly$\alpha$ Forest: Potential Neutral Hydrogen Islands at $z<6$
• Constraining the second half of reionization with the Lyman-$\beta$ forest
• Inhomogeneous Reionization Models in Cosmological Hydrodynamical Simulations
• The role of galaxies and AGN in reionising the IGM -- III : IGM-galaxy cross-correlations at z~6 from 8 quasar fields with DEIMOS and MUSE
• Imprints of temperature fluctuations on the $z\sim 5$ Lyman-$\alpha$ forest: a view from radiation-hydrodynamic simulations of reionization
• Lyman-alpha opacities at z=4-6 require low mass, radiatively-suppressed galaxies to drive cosmic reionization
• The role of galaxies and AGN in reionizing the IGM - II: metal-tracing the faint sources of reionization at $5\lesssim z\lesssim 6$
• The Evolution of the HeII-Ionizing Background at Redshifts 2.3<z<3.8 Inferred from a Statistical Sample of 24 HST/COS HeII Ly$\alpha$ Absorption Spectra
• The Predicament of Absorption-Dominated Reionization: Increased Demands on Ionizing Sources
• Evidence for a highly opaque large-scale galaxy void at the end of reionization
• JADES: Primaeval Lyman-$\alpha$ emitting galaxies reveal early sites of reionisation out to redshift $z\sim 9$
• Constraints on the End of Reionization from the Density Fields Surrounding Two Highly Opaque Quasar Sightlines
• 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
• Anomaly in the Opacity of the Post-Reionization Intergalactic Medium in the Ly$\alpha$ and Ly$\beta$ Forest
• A high space density of L* Active Galactic Nuclei at z~4 in the COSMOS field
• The Goldilocks problem of the quasar contribution to reionization
• Faint LAEs near z>4.7 CIV absorbers revealed by MUSE
• Texas Spectroscopic Search for Ly$\alpha$ Emission at the End of Reionization II. The Deepest Near-Infrared Spectroscopic Observation at $z\gtrsim 7$
• The Morphology of Reionization in a Dynamically Clumpy Universe
• Into the Lyα jungle: exploring the circumgalactic medium of galaxies at z ~ 4-5 with MUSE
• The influence of metagalactic ultra-violet background fluctuations on the high-redshift Ly$\alpha$ forest
• Constraining Reionization in Progress at z=5.7 with Lyman-$\alpha$ Emitters: Voids, Peaks, and Cosmic Variance
• The physical origin for spatially large scatter of IGM opacity at the end of reionization: the IGM Ly$\alpha$ opacity-galaxy density relation
• Exploring the cosmic dawn and epoch of reionization with 21cm line
• Ionization bias and the ghost proximity effect near $z\gtrsim 6$ quasars in the shadow of proximate absorption systems
• Revised estimates of CMB $B$-mode polarization induced by patchy reionization
• Quantifying Density-Ionization Correlations with the 21cm Power Spectrum
• SILVERRUSH. XI. Intensity Mapping for Lya Emission Extending over $100-1000$ comoving kpc around $z\sim 2-7$ LAEs with Subaru HSC-SSP and CHORUS Data
• Implications of the $z>5$ Lyman-$\alpha$ forest for the 21-cm power spectrum from the epoch of reionization
• Constraints on the state of the IGM at $z\sim 8-10$ using redshifted 21-cm observations with LOFAR
• Probing the intergalactic medium during the Epoch of Reionization using 21-cm signal power spectra
• Improving IGM temperature constraints using wavelet analysis on high-redshift quasars
• Forecasting constraints on the mean free path of ionizing photons at $z\ge 5.4$ from the Lyman-$\alpha$ forest flux auto-correlation function
• Probing patchy reionisation with JWST: IGM opacity constraints from the Lyman-$\alpha$ forest of galaxies in legacy extragalactic fields
• Probing Inhomogeneity in the Helium Ionizing UV Background
• Photometric IGM tomography with Subaru/HSC: the large-scale structure of Ly$\alpha$ emitters and IGM transmission in the COSMOS field at $z\sim 5$
• Reionizing islands with inhomogeneous recombinations
• The effect of ionizing background fluctuations on the spatial correlations of high redshift Ly$\alpha$-emitting galaxies
• Efficient Modelling of Lyman-α opacity fluctuations during late reionization epoch
• Quantifying Lyman-$\alpha$ emissions from reionization fronts
• Imaging reionization's last phases with I-front Lyman-$\alpha$ emissions
• Measuring the IGM correlation length at 5<z<6.1: a fast change at the end of Reionization
• Mapping neutral islands during end stages of reionization with photometric intergalactic medium tomography
• First Light: Switching on Stars at the Dawn of Time