The Prevalence of Galaxy Overdensities Around UV-Luminous Lyman $\alpha$ Emitters in the Epoch of Reionization

Abstract

Before the end of the epoch of reionization, the Hydrogen in the Universe was predominantly neutral. This leads to a strong attenuation of Ly$\alpha$ lines of $z\gtrsim 6$ galaxies in the intergalactic medium. Nevertheless, Ly$\alpha$ has been detected up to very high redshifts ($z\sim 9$) for several especially UV luminous galaxies. Here, we test to what extent the galaxy's local environment might impact the Ly$\alpha$ transmission of such sources. We present an analysis of dedicated Hubble Space Telescope (HST) imaging in the CANDELS/EGS field to search for fainter neighbours around three of the most UV luminous and most distant spectroscopically confirmed Ly$\alpha$ emitters: EGS-zs8-1, EGS-zs8-2 and EGSY-z8p7 at $z_{\mathrm{spec}}=7.73$, 7.48, and 8.68, respectively. We combine the multi-wavelength HST imaging with Spitzer data to reliably select $z\sim 7-9$ galaxies around the central, UV-luminous sources. In all cases, we find a clear enhancement of neighbouring galaxies compared to the expected number in a blank field (by a factor $\sim 3-9\times$). Our analysis thus reveals ubiquitous overdensities around luminous Ly$\alpha$ emitting sources in the heart of the cosmic reionization epoch. We show that our results are in excellent agreement with expectations from the Dragons simulation, confirming the theoretical prediction that the first ionized bubbles preferentially formed in overdense regions. JWST follow-up observations of the neighbouring galaxies identified here will be needed to confirm their physical association and to map out the ionized regions produced by these sources.

arXiv comment13 pages, 14 figures, Submitted to MNRAS

References in corpus (79)

• Stellar population synthesis at the resolution of 2003
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products and Mosaics
• EAZY: A Fast, Public Photometric Redshift Code
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• A Remarkably Luminous Galaxy at z=11.1 Measured with Hubble Space Telescope Grism Spectroscopy
• Keck Spectroscopy of Faint 3<z<7 Lyman Break Galaxies: - I. New constraints on cosmic reionisation from the luminosity and redshift-dependent fraction of Lyman-alpha emission
• 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
• Simulating Cosmic Reionization at Large Scales I: the Geometry of Reionization
• Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High z Surveys
• Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated Reionization Around Luminous Star Forming Systems?
• Spectral and Photometric Evolution of Young Stellar Populations: the Impact of Gaseous Emission at Various Metallicities
• The morphology of HII regions during reionization
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• Unusually Large Fluctuations in the Statistics of Galaxy Formation at High Redshift
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright, Star-Forming Galaxies with High Escape Fractions
• Spectroscopic confirmation of z~7 LBGs: probing the earliest galaxies and the epoch of reionization
• The Spectral Energy Distributions Of z~8 Galaxies From The IRAC Ultra Deep Fields: Emission Lines, Stellar Masses, And Specific Star Formation Rates At 650 Myr
• Keck Spectroscopy of Faint 3<z<8 Lyman Break Galaxies:- Evidence for a Declining Fraction of Emission Line Sources In the Redshift Range 6<z<8
• New observations of z~7 galaxies: evidence for a patchy reionization
• 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
• Lyman-alpha Emission from a Luminous z=8.68 Galaxy: Implications for Galaxies as Tracers of Cosmic Reionization
• "Big Three Dragons": a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $\mu$m, [CII] 158 $\mu$m, and Dust Continuum with ALMA
• A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE
• Z > 7 galaxies with red Spitzer/IRAC [3.6]-[4.5] colors in the full CANDELS data set: the brightest-known galaxies at Z ~ 7-9 and a probable spectroscopic confirmation at Z=7.48
• A lack of evolution in the very bright-end of the galaxy luminosity function from z = 8-10
• Observations of the Lyman-$\alpha$ Universe
• CANDELS Multiwavelength Catalogs: Source Identification and Photometry in the CANDELS Extended Groth Strip
• The changing Lya optical depth in the range 6<z<9 from MOSFIRE spectroscopy of Y-dropouts
• The WIRCam Deep Survey I: Counts, colours and mass-functions derived from near-infrared imaging in the CFHTLS deep fields
• Constraining the neutral fraction of hydrogen in the IGM at redshift 7.5
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9
• Galaxy Stellar Mass Functions from z~10 to z~6 using the Deepest Spitzer/IRAC Data: No Significant Evolution in the Stellar-to-Halo Mass Ratio of Galaxies in the First Gyr of Cosmic Time
• The Hubble Legacy Field GOODS-S Photometric Catalog
• The lack of intense Lyman~alpha in ultradeep spectra of z=7 candidates in GOODS-S: imprint of reionization?
• Star formation and the interstellar medium in z>6 UV-luminous Lyman-break galaxies
• The [OIII]$+$H$\beta$ Equivalent Width Distribution at z$\simeq$7: Implications for the Contribution of Galaxies to Reionization
• Texas Spectroscopic Search for Ly$\alpha$ Emission at the End of Reionization III. the Ly$\alpha$ Equivalent-width Distribution and Ionized Structures at $z>7$
• The Bright End of the z~9 and z~10 UV Luminosity Functions using all five CANDELS Fields
• Dark-ages reionization and galaxy formation simulation - III. Modelling galaxy formation and the epoch of reionization
• The GREATS H$\beta$+[OIII] Luminosity Function and Galaxy Properties at $\mathbf{z}\sim 8$: Walking the Way of JWST
• CANDELSz7: a large spectroscopic survey of CANDELS galaxies in the reionization epoch
• A spectroscopic search for AGN activity in the reionization era
• The Global History of Reionisation
• The THESAN project: Lyman-alpha emission and transmission during the Epoch of Reionization
• A catalog of mid-infrared sources in the Extended Groth Strip
• Ultradeep IRAC Imaging Over The HUDF And GOODS-South: Survey Design And Imaging Data Release
• Beacons into the Cosmic Dark Ages: Boosted transmission of Ly$\alpha$ from UV bright galaxies at $z\gtrsim 7$
• Onset of Cosmic Reionization: Evidence of An Ionized Bubble Merely 680 Myrs after the Big Bang
• MMT Spectroscopy of Lyman-alpha at z$\simeq$7: Evidence for Accelerated Reionization Around Massive Galaxies
• Evidence for GN-z11 as a luminous galaxy at redshift 10.957
• Overdensities of Y-dropout Galaxies from the Brightest-of-Reionizing Galaxies Survey: A Candidate Protocluster at Redshift z~8
• Probing Cosmic Dawn : Ages and Star Formation Histories of Candidate $z\ge$9 Galaxies
• The visibility of Lyman Alpha Emitters during reionization
• Spectroscopic Constraints on UV Metal Line Emission at z~6-9: The Nature of Lyman-alpha Emitting Galaxies in the Reionization-Era
• Euclid preparation: XVIII. Cosmic Dawn Survey. Spitzer observations of the Euclid deep fields and calibration fields
• Searching for Islands of Reionization: A Potential Ionized Bubble Powered by a Spectroscopic Overdensity at z = 8.7
• Newly Discovered Bright z~9-10 Galaxies and Improved Constraints on Their Prevalence Using the Full CANDELS Area
• First observational support for overlapping reionized bubbles generated by a galaxy overdensity
• Dark-ages Reionization and Galaxy Formation Simulation - X. The small contribution of quasars to reionization
• A Lyman-α protocluster at redshift 6.9
• Lyman Alpha Emitter Evolution in the Reionization Epoch
• Undetected Sources Allow Transmission of the Lyman-alpha Line From Galaxies Prior to Reionization
• Spectroscopic investigation of a reionized galaxy overdensity at z=7
• First results from Faint Infrared Grism Survey (FIGS): first simultaneous detection of Lyman-alpha emission and Lyman break from a galaxy at z=7.51
• Dark-ages Reionization & Galaxy Formation Simulation I: The dynamical lives of high redshift galaxies
• Exploring 21cm - Lyman Alpha emitter synergies for SKA
• High-redshift galaxies and low-mass stars
• Lyman-alpha transmission properties of the intergalactic medium in the CoDaII simulation
• Dark-ages Reionization and Galaxy Formation Simulation XX. The Ly$\alpha$ IGM transmission properties and environment of bright galaxies during the Epoch of Reionization
• Very Compact Dense Galaxy Overdensity with δ ~ 130 Identified at z ~ 8: Implications for Early Protocluster and Cluster-Core Formation
• A Flexible Analytic Model of Cosmic Variance in the First Billion Years
• Resolved Lyman-α properties of a luminous Lyman-break galaxy in a large ionised bubble at z = 6.53
• Dark ages reionization & galaxy formation simulation XII: Bubbles at dawn

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• Anatomy of an ionized bubble: NIRCam grism spectroscopy of the $z=6.6$ double-peaked Lyman-$\alpha$ emitter COLA1 and its environment
• Nature and Nurture? Comparing Ly$\alpha$ Detections in UV-Bright and Fainter [O III]+H$\beta$ Emitters at $z\sim 8$ With Keck/MOSFIRE
• Evidence for a low Lyman Continuum Escape fraction in three Massive, UV-bright galaxies at z > 7
• Evolution of the Lyman-α emitting fraction and UV properties of lensed star-forming galaxies between 2.9 < z < 6.7
• Mapping reionization bubbles in the JWST era II: inferring the position and characteristic size of individual bubbles
• All the Massive Galaxy Overdensities during Reionization: JWST Rest-Frame Optical Selection Reveals Young, Chemically Evolved Galaxies Embedded in Dense, Neutral Gas at z > 5
• Deep JWST spectroscopy of galaxies in a candidate ionized bubble at $z=8.7$: probing reionization at pMpc scales with Ly$\alpha$ emission
• Resolving dust and Lyα emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS