Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six

Abstract

We report the discovery of an extremely long ($\sim$110 Mpc/$h$) and dark (${\tau }_{\mathrm{eff}}\gtrsim 7$) Ly$\alpha$ trough extending down to $z\simeq 5.5$ towards the $z_{\mathrm{em}}\simeq 6.0$ quasar ULAS J0148+0600. We use these new data in combination with Ly$\alpha$ forest measurements from 42 quasars at $4.5\le z_{\mathrm{em}}\le 6.4$ to conduct an updated analysis of the line-of-sight variance in the intergalactic Ly$\alpha$ opacity over $4\le z\le 6$. We find that the scatter in transmission among lines of sight near $z\sim 6$ significantly exceeds theoretical expectations for either a uniform ultraviolet background (UVB) or simple fluctuating UVB models in which the mean free path to ionizing photons is spatially invariant. The data, particularly near $z\simeq 5.6$-5.8, instead require fluctuations in the volume-weighted hydrogen neutral fraction that are a factor of 3 or more beyond those expected from density variations alone. We argue that these fluctuations are most likely driven by large-scale variations in the mean free path, consistent with expectations for the final stages of inhomogeneous hydrogen reionization. Even by $z\simeq 5.6$, however, a large fraction of the data are consistent with a uniform UVB, and by $z\sim 5$ the data are fully consistent with opacity fluctuations arising solely from the density field. This suggests that while reionization may be ongoing at $z\sim 6$, it has fully completed by $z\sim 5$.

19 pages, 20 figures, MNRAS, in press

References in corpus (11)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• UV Luminosity Functions at z~4, 5, and 6 from the HUDF and other Deep HST ACS Fields: Evolution and Star Formation History
• 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
• Inside-out or Outside-in: The topology of reionization in the photon-starved regime suggested by Lyman-alpha forest data
• An improved measurement of the flux distribution of the Ly-alpha forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties
• A downturn in intergalactic CIV as redshift 6 is approached
• Discovery of eight z ~ 6 quasars from Pan-STARRS1
• Quasar Proximity Zones and Patchy Reionization
• Cosmic Reionization On Computers II. Reionization History and Its Back Reaction on Early Galaxies
• A Flat Photoionization Rate at 2<z<4.2: Evidence for a Stellar-Dominated UV Background and Against a Decline of Cosmic Star Formation Beyond z~3
• GRB 140515A at z=6.33: Constraints on the End of Reionization From a Gamma-ray Burst in a Low Hydrogen Column Density Environment

Cited by in corpus (146)

• The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
• The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• Introducing the THESAN project: radiation-magnetohydrodynamic simulations of the epoch of reionization
• First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
• Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionisation
• A Significantly Neutral Intergalactic Medium Around the Luminous z=7 Quasar J0252-0503
• The Neutral Hydrogen Cosmological Mass Density at z=5
• The Impact of the First Galaxies on Cosmic Dawn and Reionization
• The THESAN project: properties of the intergalactic medium and its connection to Reionization-era galaxies
• Lyman-alpha emitters gone missing: evidence for late reionization?
• Constraining the radio-loud fraction of quasars at z>5.5
• XQ-100: A legacy survey of one hundred 3.5 < z < 4.5 quasars observed with VLT/XSHOOTER
• Self-Consistent Modeling of Reionization in Cosmological Hydrodynamical Simulations
• EIGER V. Characterizing the Host Galaxies of Luminous Quasars at $z\gtrsim 6$
• Long Dark Gaps in the Ly$\beta$ Forest at $z<6$: Evidence of Ultra Late Reionization from XQR-30 Spectra
• IGM damping wing constraints on reionisation from covariance reconstruction of two $z\gtrsim 7$ QSOs
• (Nearly) Model-Independent Constraints on the Neutral Hydrogen Fraction in the Intergalactic Medium at $z\sim 5-7$ Using Dark Pixel Fractions in Ly$\alpha$ and Ly$\beta$ Forests
• A VLT/FORS2 view at $z\sim 6$: Lyman-$\alpha$ emitter fraction and galaxy physical properties at the edge of the epoch of cosmic reionization
• A survey of luminous high-redshift quasars with SDSS and WISE II. the bright end of the quasar luminosity function at z ~ 5
• XQR-30: the ultimate XSHOOTER quasar sample at the reionization epoch
• Searching for Islands of Reionization: A Potential Ionized Bubble Powered by a Spectroscopic Overdensity at z = 8.7
• Chasing the Tail of Cosmic Reionization with Dark Gap Statistics in the Ly$\alpha$ Forest over $5<z<6$
• Minor Contribution of Quasars to Ionizing Photon Budget at z~6: Update on Quasar Luminosity Function at the Faint-end with Subaru/Suprime-Cam
• The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium
• Discovery of Eight z ~ 6 Quasars in the Sloan Digital Sky Survey Overlap Regions
• A New Precision Measurement of the Small-Scale Line-of-Sight Power Spectrum of the Ly$\alpha$ Forest
• The short ionizing photon mean free path at z=6 in Cosmic Dawn III, a new fully-coupled radiation-hydrodynamical simulation of the Epoch of Reionization
• Detecting and Characterizing Young Quasars II: Four Quasars at $z\sim 6$ with Lifetimes $<10^4$ years
• An Introductory Review on Cosmic Reionization
• Chronicling the reionization history at $6\lesssim z\lesssim 7$ with emergent quasar damping wings
• Damping Wing-Like Features in the Stacked Ly$\alpha$ Forest: Potential Neutral Hydrogen Islands at $z<6$
• XQR-30: Black Hole Masses and Accretion Rates of 42 z>6 Quasars
• Cosmic Reionization After Planck and Before JWST: An Analytic Approach
• Peering into cosmic reionization: the Ly$\alpha$ visibility evolution from galaxies at $z$ = 4.5-8.5 with JWST
• Damping wings in the Lyman-α forest: a model-independent measurement of the neutral fraction at 5.4<z<6.1
• A deep search for metals near redshift 7: the line-of-sight towards ULAS J1120+0641
• The Reionization of Carbon
• Large scale simulations of H and He reionization and heating driven by stars and more energetic sources
• AMBER: A Semi-numerical Abundance Matching Box for the Epoch of Reionization
• The Pan-STARRS1 $\mathbf{z}>5.6$ Quasar Survey: III. The $\mathbf{z}\approx 6$ Quasar Luminosity Function
• The XQR-30 Metal Absorber Catalog: 778 Absorption Systems Spanning 2 < z < 6.5
• 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
• Constraining the reionization history using deep learning from 21cm tomography with the Square Kilometre Array
• 21cmEMU: an emulator of 21cmFAST summary observables
• Dark-ages Reionization and Galaxy Formation Simulation XX. The Ly$\alpha$ IGM transmission properties and environment of bright galaxies during the Epoch of Reionization
• Measuring the reionization optical depth without large-scale CMB polarization
• A Short Introduction to Reionization Physics
• The need for obscured supermassive black hole growth to explain quasar proximity zones in the epoch of reionization
• The Lyman continuum escape fraction and the Mean Free Path of hydrogen ionizing photons for bright z~4 QSOs from SDSS DR14
• Warm Dark Matter and Cosmic Reionization
• Small-scale structure and the Lyman-$\alpha$ forest baryon acoustic oscillation feature
• The impact of non-Gaussianity on the error covariance for observations of the Epoch of Reionization 21-cm power spectrum
• A self-consistent 3D model of fluctuations in the helium-ionizing background
• Models of the Cosmological 21 cm Signal from the Epoch of Reionization Calibrated with Lyman-alpha and CMB Data
• Revealing the cosmic reionisation history with fast radio bursts in the era of Square Kilometre Array
• Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1
• The Faint Host Galaxies of C IV Absorbers at z > 5
• The effect of inhomogeneous reionisation on the Lyman-$\alpha$ forest power spectrum at redshift $z>4$: implications for thermal parameter recovery
• Probing the thermal history during reionization using a semi-numerical photon-conserving code SCRIPT
• Highly r-process enhanced stars in ultra-faint dwarf galaxies
• Examining the Decline in the C IV Content of the Universe over 4.3 < z < 6.3 using the E-XQR-30 Sample
• The Morphology of Reionization in a Dynamically Clumpy Universe
• The impact of non-Gaussianity on the Epoch of Reionization parameter forecast using 21-cm power spectrum measurements
• The evolution of the UV luminosity function of globular clusters in the E-MOSAICS simulations
• New quasar proximity zone size measurements at $z\sim 6$ using the enlarged XQR-30 sample
• The comoving mass density of MgII from $z\sim 2$ to $5.5$
• Lyman Continuum Galaxy Candidates in COSMOS
• First Detection of Cosmic Microwave Background Lensing and Lyman-α Forest Bispectrum
• The influence of metagalactic ultra-violet background fluctuations on the high-redshift Ly$\alpha$ forest
• Constraining the reionization and thermal history of the Universe using a semi-numerical photon-conserving code SCRIPT
• Patchy Kinetic Sunyaev-Zel'dovich Effect with Controlled Reionization History and Morphology
• Astraeus VI: Hierarchical assembly of AGN and their large-scale effect during the Epoch of Reionization
• Simulated metal and HI absorption lines at the conclusion of Reionization
• Constraining Reionization in Progress at z=5.7 with Lyman-$\alpha$ Emitters: Voids, Peaks, and Cosmic Variance
• The detectability of strong 21 centimetre forest absorbers from the diffuse intergalactic medium in late reionisation models
• Evidence of Pop~III stars' chemical signature in neutral gas at z~6. A study based on the E-XQR-30 spectroscopic sample
• CHORUS. I. Cosmic HydrOgen Reionization Unveiled with Subaru: Overview
• The physical origin for spatially large scatter of IGM opacity at the end of reionization: the IGM Ly$\alpha$ opacity-galaxy density relation
• Early Results from GLASS-JWST XXIII: The transmission of Lyman-alpha from UV-faint z ~ 3-6 galaxies
• Microquasars as heating sources of the intergalactic medium during reionisation of the Universe
• Exploring the cosmic dawn and epoch of reionization with 21cm line
• A double-peaked Lyman-$\alpha$ emitter with a strong blue peak multiply imaged by the galaxy cluster RXC J0018.5+1626
• Late-end reionization with ATON-HE: towards constraints from Lyman-$\alpha$ emitters observed with JWST
• POLAR -- I: linking the 21-cm signal from the epoch of reionization to galaxy formation
• Modelling the star-formation activity and ionizing properties of high-redshift galaxies
• Prospects for kSZ${}^2$-Galaxy Cross-Correlations during Reionization
• 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
• Possible evidence for a large-scale enhancement in the Lyman-$\alpha$ forest power spectrum at redshift $\text{z}\ge 4$
• Persistent topology of the reionization bubble network. II: Evolution & Classification
• Conditions for direct black hole seed collapse near a radio-loud quasar 1 Gyr after the Big Bang
• Constraints on the state of the IGM at $z\sim 8-10$ using redshifted 21-cm observations with LOFAR
• Wavelet Based Statistics for Enhanced 21cm EoR Parameter Constraints
• A galaxy-free phenomenological model for the 21-cm power spectrum during reionization
• The THESAN-ZOOM project: Population III star formation continues until the end of reionization
• CII and HI 21-cm line intensity mapping from the EoR: Impact of the light-cone effect on auto and cross-power spectra
• CHORUS IV: Mapping the Spatially Inhomogeneous Cosmic Reionization with Subaru HSC
• A Generative Model for Quasar Spectra
• Distinguishing reionization models using the largest cluster statistics of the 21-cm maps
• A fast method of reionization parameter space exploration using GPR trained SCRIPT
• Cosmic Reionization on Computers: Physical Origin of Long Dark Gaps in Quasar Absorption Spectra
• Probing quasar lifetimes with proximate $21$-centimetre absorption in the diffuse intergalactic medium at redshifts $z\ge 6$
• 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
• The environments and hosts of metal absorption at z>5
• Maximal X-ray feedback in the pre-reionization universe
• New Interpretations of the Cosmological Preference for a Negative Neutrino Mass
• 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
• Line of sight anisotropies in the Cosmic Dawn and EoR 21-cm power spectrum
• Optical and near-infrared spectroscopy of quasars at $z>6.5$: public data release and composite spectrum
• Understanding the "Feeble Giant" Crater II with tidally stretched Wave Dark Matter
• The Lyman-limit photon mean free path at the end of late reionisation in the Sherwood-Relics simulations
• Ly$\alpha$NNA: A Deep Learning Field-level Inference Machine for the Lyman-$\alpha$ Forest
• Studying the Multi-frequency Angular Power Spectrum of the Cosmic Dawn 21-cm Signal
• Interpreting the HI 21-cm cosmology maps through Largest Cluster Statistics -- I: Impact of the synthetic SKA1-Low observations
• Revealing new high redshift quasar populations through Gaussian mixture model selection
• Photometric IGM tomography with Subaru/HSC: the large-scale structure of Ly$\alpha$ emitters and IGM transmission in the COSMOS field at $z\sim 5$
• Prospects of a statistical detection of the 21-cm forest and its potential to constrain the thermal state of the neutral IGM during reionization
• HeII Ly$\alpha$ Transmission Spikes and Absorption Troughs in Eight High-resolution Spectra Probing the End of HeII Reionization
• Lognormal semi-numerical simulations of the Lyman-$\alpha$ forest: comparison with full hydrodynamic simulations
• The Qz5 Survey (I): How the HI Mass Density of the Universe Evolves With Cosmic Time
• Assuming Ionization Equilibrium and the Impact on the Lyman-$\alpha$ Forest Power Spectrum during the End of Reionization at $8\ge z\ge 5$
• Reionizing islands with inhomogeneous recombinations
• Ly$\alpha$ Emission from [OIII] Emitters Near Reionization: The role of environment in galaxy Ly$\alpha$ detection
• The effect of ionizing background fluctuations on the spatial correlations of high redshift Ly$\alpha$-emitting galaxies
• Unveiling the Phase Transition of the Universe During the Reionization Epoch with Lyman-alpha
• Constraints on the galaxy formation models during epoch of reionization with high redshift observations
• GRBs as Probes of the IGM
• An emulator for the ionizing photon mean free path in ultra-high resolution simulations: the implications of mean free path measurements for the reionization history
• 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
• Imaging reionization's last phases with I-front Lyman-$\alpha$ emissions
• Fast Luminous Blue Transients in the Reionization Era and Beyond
• Quantifying Lyman-$\alpha$ emissions from reionization fronts
• The effect of helium reionization on the Lyman-alpha forest hydrogen flux statistics
• Modified Cosmology or Modified Galaxy Astrophysics is Driving the z>6 JWST Results? CMB Experiments can discover the Origin in the Near Future
• Studying dark gaps in Ly-$\alpha$ forest transmission with large reionization simulations
• First Light: Switching on Stars at the Dawn of Time
• Optimizing Foreground Modelling for Global 21cm Cosmology with GPU-Accelerated Nested Sampling
• Nearest Neighbour-Based Statistics for 21cm-Galaxy Cross-Correlations in the Epoch of Reionization
• Neural network emulator to constrain the high-$z$ IGM thermal state from Lyman-$\alpha$ forest flux auto-correlation function
• Galaxy Proximate Damped Lyman-Alpha Systems and HI Reionization Topology in TECHNICOLOR DAWN