Lyman-alpha Emitters in Ionized Bubbles: Constraining the Environment and Ionized Fraction

Abstract

Lyman-alpha emitters (LAEs) are excellent probes of the reionization process, as they must be surrounded by large ionized bubbles in order to be visible during the reionization era. Large ionized regions are thought to correspond to over-dense regions and may be protoclusters, making them interesting test-beds for early massive structures. Close associations containing several LAEs are often assumed to mark over-dense, ionized bubbles. Here, we develop the first framework to quantify the ionization and density fields of high-z galaxy associations. We explore the interplay between (i) the large-scale density of a survey field, (ii) Poisson noise due to the small number density of bright sources at high redshifts (z~7), and (iii) the effects of the ionized fraction on the observation of LAEs. We use Bayesian statistics, a simple model of reionization, and a Monte-Carlo simulation to construct a more comprehensive method for calculating the large-scale density of LAE regions than previous works. We find that Poisson noise has a strong effect on the inferred density of a region and show how the ionized fraction can be inferred. We then apply our framework to the strongest association yet identified: Hu et al. (2021) found 14 LAEs in a volume of ~50,000 cMpc^3 inside the COSMOS field at z~7. We show that this is most likely a 2.5-sigma over-density inside of an ionized or nearly ionized bubble. We also show that this LAE association implies that the global ionized fraction is Q = 0.60 (+0.08,-0.09), within the context of a simple reionization model.

arXiv comment14 pages, 14 figures, submitted to MNRAS

References in corpus (69)

• Planck 2015 results. XIII. Cosmological parameters
• Baryonic Features in the Matter Transfer Function
• An analytic model for the spatial clustering of dark matter haloes
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Model-independent evidence in favor of an end to reionization by z~6
• Hydrodynamic Simulations of Galaxy Formation. II. Photoionization and the Formation of Low Mass Galaxies
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• Reionization of the Intergalactic Medium and the Damping Wing of the Gunn-Peterson Trough
• Spectroscopic Confirmation of Three z-Dropout Galaxies at z = 6.844 - 7.213: Demographics of Lyman-Alpha Emission in z ~ 7 Galaxies
• The Universe is Reionizing at z~7: Bayesian Inference of the IGM Neutral Fraction Using Ly$\alpha$ Emission from Galaxies
• Pōniuā'ena: A Luminous $z=7.5$ Quasar Hosting a 1.5 Billion Solar Mass Black Hole
• The morphology of HII regions during reionization
• Luminosity functions of Lyman-alpha emitters at z=6.5, and z=5.7: evidence against reionization at z=6
• Quantitative Constraints on the Reionization History from the IGM Damping Wing Signature in Two Quasars at z > 7
• Spectroscopic confirmation of z~7 LBGs: probing the earliest galaxies and the epoch of reionization
• The Galaxy UV Luminosity Function Before the Epoch of Reionization
• Keck Spectroscopy of Faint 3<z<7 Lyman Break Galaxies:- II. A High Fraction of Line Emitters at Redshift Six
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Completing the Census of Ly-alpha Emitters at the Reionization Epoch
• The Discovery of Primeval Large-Scale Structures with Forming Clusters at Redshift 6
• Probing reionization with Lyman-alpha emission lines
• Galaxy Protoclusters as Drivers of Cosmic Star-Formation History in the First 2 Gyr
• 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
• Observations of the Lyman-$\alpha$ Universe
• A Significantly Neutral Intergalactic Medium Around the Luminous z=7 Quasar J0252-0503
• Constraining the neutral fraction of hydrogen in the IGM at redshift 7.5
• Self-regulated reionization
• The Galaxy Luminosity Function during the Reionization Epoch
• A Simple Technique for Predicting High-Redshift Galaxy Evolution
• The mean free path of ionizing photons at 5 < z < 6: evidence for rapid evolution near reionization
• Are we witnessing the epoch of reionisation at $z=7.1$ from the spectrum of J1120+0641?
• The Detectability of High Redshift Lyman Alpha Emission Lines Prior to the Reionization of the Universe
• 21cmFAST v3: A Python-integrated C code forgenerating 3D realizations of the cosmic 21cm signal
• Texas Spectroscopic Search for Ly$\alpha$ Emission at the End of Reionization III. the Ly$\alpha$ Equivalent-width Distribution and Ionized Structures at $z>7$
• The Earliest Luminous Sources and the Damping Wing of the Gunn-Peterson Trough
• A physical model for the 0 < z < 8 redshift evolution of the galaxy UV luminosity and stellar mass functions
• Density split statistics: Cosmological constraints from counts and lensing in cells in DES Y1 and SDSS data
• The Effects of Reionization on Lyman-alpha Galaxy Surveys
• Density split statistics: joint model of counts and lensing in cells
• Lyman-alpha Emitters During the Early Stages of Reionization
• Long Dark Gaps in the Ly$\beta$ Forest at $z<6$: Evidence of Ultra Late Reionization from XQR-30 Spectra
• Onset of Cosmic Reionization: Evidence of An Ionized Bubble Merely 680 Myrs after the Big Bang
• A physical understanding of how reionization suppresses accretion onto dwarf halos
• IGM damping wing constraints on reionisation from covariance reconstruction of two $z\gtrsim 7$ QSOs
• MMT Spectroscopy of Lyman-alpha at z$\simeq$7: Evidence for Accelerated Reionization Around Massive Galaxies
• Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization
• Constraining the Topology of Reionization Through Lyman-alpha Absorption
• A Minimalist Feedback-Regulated Model for Galaxy Formation During the Epoch of Reionization
• Overdensities of Y-dropout Galaxies from the Brightest-of-Reionizing Galaxies Survey: A Candidate Protocluster at Redshift z~8
• The Evolution of the Lyman-Alpha Luminosity Function During Reionization
• SILVERRUSH. VI. A simulation of Ly$\alpha$ emitters in the reionization epoch and a comparison with Subaru Hyper Suprime-Cam survey early data
• Measuring the Cosmic Equation of State with Counts of Galaxies II: Error Budget for the DEEP2 Redshift Survey
• LAGER Ly$\alpha$ Luminosity Function at $z\sim 7$, Implications for Reionization
• A Lyman-α protocluster at redshift 6.9
• The Distribution of Bubble Sizes During Reionization
• Undetected Sources Allow Transmission of the Lyman-alpha Line From Galaxies Prior to Reionization
• Strong Ly$\alpha$ Emission in an Overdense Region at $z=6.8$: A Very Large ($R\sim 3$ physical Mpc) Ionized Bubble in COSMOS?
• An Empirically-Calibrated Model For Interpreting the Evolution of Galaxies During the Reionization Era
• CHORUS II. Subaru/HSC Determination of the Ly$\alpha$ Luminosity Function at $z=7.0$: Constraints on Cosmic Reionization Model Parameter
• A lensed protocluster candidate at $z=7.66$ identified in JWST observations of the galaxy cluster SMACS0723-7327
• The Predicament of Absorption-Dominated Reionization: Increased Demands on Ionizing Sources
• Estimating Luminosity Function Constraints from High-Redshift Galaxy Surveys
• Nonlinear Bias of Cosmological Halo Formation in the Early Universe
• A Flexible Analytic Model of Cosmic Variance in the First Billion Years
• Understanding large-scale structure in the SSA22 protocluster region using cosmological simulations
• The PDF perspective on the tracer-matter connection: Lagrangian bias and non-Poissonian shot noise
• MOS spectroscopy of protocluster candidate galaxies at z=6.5
• CHORUS IV: Mapping the Spatially Inhomogeneous Cosmic Reionization with Subaru HSC
• Galaxy Statistics in Pencil-beam Surveys at High Redshifts

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• JADES: Primaeval Lyman-$\alpha$ emitting galaxies reveal early sites of reionisation out to redshift $z\sim 9$
• Ly$\alpha$ Emission from [OIII] Emitters Near Reionization: The role of environment in galaxy Ly$\alpha$ detection
• Ciii]$\lambda 1909$ emission as an alternative to Ly$\alpha$ in the reionization era: the dependence of Ciii] and Ly$\alpha$ at $3<z<4$ from the VANDELS survey