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

Abstract

The high-redshift progenitors of present-day galaxy clusters are believed to substantially contribute to the global star-formation rate density and drive the large-scale reionization of the Universe. Here we present a blind and unbiased search for and characterization of galaxy overdensities during the reionization epoch at redshifts $z\sim 5.5-7$, based on rest-frame optical JWST/NIRCam grism spectroscopy of the Abell\,2744 lensing field as part of the JWST-ALT survey. Using a physically-motivated, cosmological inference Friends-of-Friends (FoF) algorithm, we identify six galaxy overdensities, including five robust systems at $z=5.66$ to $6.77$. They are all characterized by total halo masses $M_{\mathrm{halo}}\gtrsim 10^{11}{M}_{\odot }$ inferred from a range of proxies. We find that the galaxy members in these overdense environments are on average less massive though equally metal-rich, and generally comprised of younger stellar populations as indicated from their bluer spectral slopes less prominent Balmer breaks, than field galaxies at similar redshifts. Further, we use this novel rest-frame optical selection of galaxy proto-clusters to infer the fraction and 3D distribution of strong Lyman-$\alpha$ emitters (LAEs) and damped Lyman-$\alpha$ absorbers (DLAs) in the overdensity environments. We find that two out of six galaxy overdensities have excess \hi\ absorption compared to the field-average, while the other four are consistent within their large scatter in density. These results present the first direct observational constraints on the tomography of the dense, neutral gas reservoirs in large-scale galaxy overdensities at $z>5$ and highlight the limitations of pre-JWST searches for reionization-era galaxy overdensities relying on the detection of strong LAEs alone.[Abridged]

13 pages, 9 figures, submitted

References in corpus (55)

• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• How Do Galaxies Get Their Gas?
• The Average Star Formation Histories of Galaxies in Dark Matter Halos from z=0-8
• First results from the IllustrisTNG simulations: matter and galaxy clustering
• Galaxy Bimodality due to Cold Flows and Shock Heating
• Cold streams in early massive hot haloes as the main mode of galaxy formation
• First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies
• First results from the IllustrisTNG simulations: the galaxy color bimodality
• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• First results from the IllustrisTNG simulations: A tale of two elements -- chemical evolution of magnesium and europium
• The physics driving the cosmic star formation history
• Damped Lyman alpha Systems
• Stellar Population Inference with Prospector
• Deriving Physical Properties from Broadband Photometry with Prospector: Description of the Model and a Demonstration of its Accuracy Using 129 Galaxies in the Local Universe
• Reionization of the Inhomogeneous Universe
• Two Remarkably Luminous Galaxy Candidates at $z\approx 10-12$ Revealed by JWST
• Galaxy and Mass Assembly (GAMA): The GAMA Galaxy Group Catalogue (G3Cv1)
• Ancient Light from Young Cosmic Cities: Physical and Observational Signatures of Galaxy Proto-Clusters
• Clues to the Origin of the Mass-Metallicity Relation: Dependence on Star Formation Rate and Galaxy Size
• Implications for the Cosmic Reionization from the Optical Afterglow Spectrum of the Gamma-Ray Burst 050904 at z = 6.3
• The realm of the galaxy protoclusters
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• Galaxy Protoclusters as Drivers of Cosmic Star-Formation History in the First 2 Gyr
• The brightest galaxies at Cosmic Dawn
• On the Stellar Populations of Galaxies at z=9-11: The Growth of Metals and Stellar Mass at Early Times
• Long troughs in the Lyman-$\alpha$ forest below redshift 6 due to islands of neutral hydrogen
• The overdensity and masses of the friends-of-friends halos and universality of the halo mass function
• EIGER II. first spectroscopic characterisation of the young stars and ionised gas associated with strong H$\beta$ and [OIII] line-emission in galaxies at z=5-7 with JWST
• EIGER I. a large sample of [OIII]-emitting galaxies at $5.3<z<6.9$ and direct evidence for local reionization by galaxies
• Voigt Profile Fitting to Quasar Absorption Lines: An Analytic Approximation to the Voigt-Hjerting Function
• UNCOVERing the extended strong lensing structures of Abell 2744 with the deepest JWST imaging
• RUBIES: a complete census of the bright and red distant Universe with JWST/NIRSpec
• The JWST-PRIMAL Legacy Survey. A JWST/NIRSpec reference sample for the physical properties and Lyman-$\alpha$ absorption and emission of $\sim 500$ galaxies at $z=5.5-13.4$
• Instability of Supersonic Cold Streams Feeding Galaxies I: Linear Kelvin-Helmholtz Instability with Body Modes
• Resolving shocks and filaments in galaxy formation simulations: effects on gas properties and star formation in the circumgalactic medium
• Spectroscopic investigation of a reionized galaxy overdensity at z=7
• The JWST Advanced Deep Extragalactic Survey: Discovery of an Extreme Galaxy Overdensity at $z=5.4$ with JWST/NIRCam in GOODS-S
• Evidence for Cold-stream to Hot-accretion Transition as Traced by Lyα Emission from Groups and Clusters at 2 < z < 3.3
• Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA): The core of the highest redshift galaxy overdensity at $z=7.88$ confirmed by NIRSpec/JWST
• A lensed protocluster candidate at $z=7.66$ identified in JWST observations of the galaxy cluster SMACS0723-7327
• The Prevalence of Galaxy Overdensities Around UV-Luminous Lyman $\alpha$ Emitters in the Epoch of Reionization
• Identification of High-Redshift Galaxy Overdensities in GOODS-N and GOODS-S
• JADES: Primaeval Lyman-$\alpha$ emitting galaxies reveal early sites of reionisation out to redshift $z\sim 9$
• Very Compact Dense Galaxy Overdensity with δ ~ 130 Identified at z ~ 8: Implications for Early Protocluster and Cluster-Core Formation
• Probing the existence of a rich galaxy overdensity at z=5.2
• Constraints on the $z\sim 6-13$ intergalactic medium from JWST spectroscopy of Lyman-alpha damping wings in galaxies
• Uncovering the physical origin of the prominent Lyman-$\alpha$ emission and absorption in GS9422 at $z=5.943$
• A Radio-to-millimeter Census of Star-forming Galaxies in Protocluster 4C~23.56 at z = 2.5 : Global and local gas kinematics
• Novel $z\sim 10$ auroral line measurements extend the gradual offset of the FMR deep into the first Gyr of cosmic time
• Before its time: a remarkably evolved protocluster core at z=7.88
• Rapid, out of equilibrium metal enrichment indicated by a flat mass-metallicity relation at z~6 from NIRCam grism spectroscopy
• Metal enrichment of galaxies in a massive node of the Cosmic Web at $z\sim 3$

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