Shadow of a Colossus: A z=2.45 Galaxy Protocluster Detected in 3D Ly-a Forest Tomographic Mapping of the COSMOS Field

Abstract

Using moderate-resolution optical spectra from 58 background Lyman-break galaxies and quasars at $z\sim 2.3-3$ within a $11.5^{\prime }\times 13.5^{\prime }$ area of the COSMOS field ($\sim 1200{\mathrm{deg}}^2$ projected area density or $\sim 2.4h^{-1}\mathrm{Mpc}$ mean transverse separation), we reconstruct a 3D tomographic map of the foreground Ly$\alpha$ forest absorption at $2.2<z<2.5$ with an effective smoothing scale of ${\sigma }_{3d}\approx 3.5h^{-1}\mathrm{Mpc}$ comoving. Comparing with 61 coeval galaxies with spectroscopic redshifts in the same volume, we find that the galaxy positions are clearly biased towards regions with enhanced IGM absorption in the tomographic map. We find an extended IGM overdensity with deep absorption troughs at $z=2.45$ associated with a recently-discovered galaxy protocluster at the same redshift. Based on simulations matched to our data, we estimate the enclosed dark matter mass within this IGM overdensity to be $M_{\mathrm{dm}}(z=2.45)=(9\pm 4)\times 10^{13}{h}^{-1}{\mathrm{M}}_{\odot }$, and argue based on this mass and absorption strength that it will form at least one $z\sim 0$ galaxy cluster with $M(z=0)=(3\pm 2)\times 10^{14}{h}^{-1}{\mathrm{M}}_{\odot }$, although its elongated nature suggests that it will likely collapse into two separate clusters. We also point out a compact overdensity of six MOSDEF galaxies at $z=2.30$ within a $r\sim 1h^{-1}\mathrm{Mpc}$ radius and $\Delta z\sim 0.006$, which does not appear to have a large associated IGM overdensity. These results demonstrate the potential of Ly$\alpha$ forest tomography on larger volumes to study galaxy properties as a function of environment, as well as revealing the large-scale IGM overdensities associated with protoclusters and other features of large-scale structure.

To be submitted to ApJ. Figure 3 can be viewed on Youtube: https://youtu.be/KeW1UJOPMYI

References in corpus (19)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• COSMOS Photometric Redshifts with 30-bands for 2-deg2
• zCOSMOS: A Large VLT/VIMOS redshift survey covering 0 < z < 3 in the COSMOS field
• The MOSFIRE Deep Evolution Field (MOSDEF) Survey: Rest-Frame Optical Spectroscopy for ~1500 H-Selected Galaxies at 1.37 < z < 3.8
• The VIMOS Ultra-Deep Survey: ~10,000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2<z<~6
• Stellar masses from the CANDELS survey: the GOODS-South and UDS fields
• Quasar Quartet Embedded in Giant Nebula Reveals Rare Massive Structure in Distant Universe
• A Direct Precision Measurement of the Intergalactic Lyman-alpha Opacity at 2<z<4.2
• A massive, distant proto-cluster at z=2.47 caught in a phase of rapid formation?
• Possible evidence for an inverted temperature-density relation in the intergalactic medium from the flux distribution of the Lyman-alpha forest
• Lyman-alpha Forest Tomography from Background Galaxies: The First Megaparsec-Resolution Large-Scale Structure Map at z>2
• Surveying Galaxy Proto-clusters in Emission: A Large-scale Structure at z=2.44 and the Outlook for HETDEX
• IGM Constraints from the SDSS-III/BOSS DR9 Ly-alpha Forest Flux Probability Distribution Function
• KECK/MOSFIRE spectroscopic confirmation of a Virgo-like cluster ancestor at z=2.095
• A z=2.5 protocluster associated with the radio galaxy MRC 2104-242: star formation and differing mass functions in dense environments
• A proto-cluster at z=2.45
• Discovery of a Very Large Structure at Z=3.78
• Protocluster Discovery in Tomographic Ly$\alpha$ Forest Flux Maps
• Cluster candidates around low power radio-galaxies at z~1-2 in COSMOS

Cited by in corpus (70)

• Galaxy Protoclusters as Drivers of Cosmic Star-Formation History in the First 2 Gyr
• The Ubiquity of Coeval Starbursts in Massive Galaxy Cluster Progenitors
• The progeny of a Cosmic Titan: a massive multi-component proto-supercluster in formation at z=2.45 in VUDS
• First Data Release of the COSMOS Lyman-Alpha Mapping And Tomography Observations: 3D Lyman-$\alpha$ Forest Tomography at 2.05 < z < 2.55
• The VIMOS Ultra Deep Survey: Emerging from the Dark, a Massive Proto-Cluster at z~4.57
• Spectroscopic Confirmation of a Protocluster at $z=3.37$ with a High Fraction of Quiescent Galaxies
• Evidence for Large-Scale Fluctuations in the Metagalactic Ionizing Background Near Redshift Six
• MAHALO Deep Cluster Survey I. Accelerated and enhanced galaxy formation in the densest regions of a protocluster at z=2.5
• MAHALO Deep Cluster Survey II. Characterizing massive forming galaxies in the Spiderweb protocluster at z=2.2
• The VIMOS Ultra Deep Survey: The reversal of the star-formation rate $-$ density relation at $2<z<5$
• Confirming Herschel candidate protoclusters from ALMA/VLA CO observations
• LATIS: The Ly$\alpha$ Tomography IMACS Survey
• Large scale structure around a z=2.1 cluster
• On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Proto-Clusters at z~2.0-2.5
• Galaxies Probing Galaxies in PRIMUS - I. Sample, Spectroscopy, and Characteristics of the z~0.5 MgII-Absorbing Circumgalactic Medium
• Comprehensive Gas Characterization of a $z=2.5$ Protocluster: A Cluster Core Caught in the Beginning of Virialization?
• TARDIS Paper I: A Constrained Reconstruction Approach to Modeling the z~2.5 Cosmic Web Probed by Lyman-alpha Forest Tomography
• Galaxies Probing Galaxies in PRIMUS - II. The Coherence Scale of the Cool Circumgalactic Medium
• Second Data Release of the COSMOS Lyman-alpha Mapping and Tomographic Observation: The First 3D Maps of the Detailed Cosmic Web at 2.05<z<2.55
• Environmental Dependence of Galactic Properties Traced by Ly$\alpha$ Forest Absorption: Diversity among Galaxy Populations
• A tomographic map of the large-scale matter distribution using the eBOSS Stripe 82 Ly-$\alpha$ forest
• Establishing a New Technique for Discovering Large-Scale Structure Using the ORELSE Survey
• Revealing the z~2.5 Cosmic Web With 3D Lyman-Alpha Forest Tomography: A Deformation Tensor Approach
• Predicted future fate of COSMOS galaxy protoclusters over 11 Gyr with constrained simulations
• BIRTH of the COSMOS Field: Primordial and Evolved Density Reconstructions During Cosmic High Noon
• Evaluating Lya Emission as a Tracer of the Largest Cosmic Structure at z~2.47
• The UV Luminosity Function of Protocluster Galaxies at $z\sim 4$: the Bright-end Excess and the Enhanced Star Formation Rate Density
• Probing Feedback via IGM tomography and Ly$\alpha$ forest with Subaru PFS, TMT/ELT, and JWST
• A detailed study of massive galaxies in a protocluster at z=3.13
• Spectroscopic Confirmation of two Extremely Massive Protoclusters BOSS1244 and BOSS1542 at $z=2.24$
• Simba: The average properties of the circumgalactic medium of $2\le z\le 3$ quasars are determined primarily by stellar feedback
• Mapping quasar light echoes in 3D with Lyα forest tomography
• Statistical correlation between the distribution of Ly$\alpha$ emitters and IGM HI at $z\sim 2.2$ mapped by Subaru/Hyper Suprime-Cam
• A Fundamental Test for Galaxy Formation Models: Matching the Lyman-$\alpha$ Absorption Profiles of Galactic Halos over Three Decades in Distance
• A population of ultraviolet-dim protoclusters detected in absorption
• Large Scale Structures in COSMOS2020: Evolution of Star Formation Activity in Different Environments at 0.4 < z < 4
• Characterizing Protoclusters and Protogroups at z $\sim$ 2.5 Using Ly$\alpha$ Tomography
• TARDIS Paper II: Synergistic Density Reconstruction from Lyman-alpha Forest and Spectroscopic Galaxy Surveys with Applications to Protoclusters and the Cosmic Web
• Cosmic Galaxy-IGM HI Relation at $z\sim 2-3$ Probed in the COSMOS/UltraVISTA $1.6$ deg${}^2$ Field
• Simulating MOS science on the ELT: Ly$\alpha$ forest tomography
• Understanding large-scale structure in the SSA22 protocluster region using cosmological simulations
• Bayesian cosmic density field inference from redshift space dark matter maps
• The stellar mass function of quiescent galaxies in 2 < z < 2.5 protoclusters
• Observational Evidence for Large-Scale Gas Heating in a Galaxy Protocluster at z=2.30
• Measuring alignments between galaxies and the cosmic web at $z\sim 2-3$ using IGM tomography
• Catch Me if You Can: Biased Distribution of Ly$\alpha$-emitting Galaxies according to the Viewing Direction
• 3D Distribution Map of HI Gas and Galaxies Around an Enormous Ly$\alpha$ Nebula and Three QSOs at $z=2.3$ Revealed by the HI Tomographic Mapping Technique
• Cosmological 3D HI Gas Map with HETDEX Ly$\alpha$ Emitters and eBOSS QSOs at $z=2$: IGM-Galaxy/QSO Connection and a $\sim$ 40-Mpc Scale Giant HII Bubble Candidate
• Searching for the shadows of giants: characterising protoclusters with line of sight Lyman-α absorption
• Discovering Large-Scale Structure at $2<z<5$ in the C3VO Survey
• The COSMOS-Web deep galaxy group catalog up to $z=3.7$
• Morphological Evolution of the Hosts of Far-Infrared/Submillimeter Galaxies
• Constraining the Fluctuating Gunn-Peterson Approximation Using Lyman-$\alpha$ Forest Tomography at $z=2$
• Detecting preheating in proto-clusters with Lyman-$\alpha$ Forest Tomography
• The AGN fraction in high-redshift protocluster candidates selected by Planck and Herschel
• Searching for the shadows of giants II: the effect of local ionisation on the Lyman-$\alpha$ absorption signatures of protoclusters at redshift $z\sim 2.4$
• Discovery of a Low-Redshift Damped Ly$\alpha$ System in a Foreground Extended Disk Using a Starburst Galaxy Background Illuminator
• A Novel Estimator for the Equation of State of the IGM by Ly$\alpha$ Forest Tomography
• Connection Between Galaxies and HI in the Circumgalactic and Intergalactic Media: Variation According to Galaxy Stellar Mass and Star-formation Activity
• Photometric IGM tomography with Subaru/HSC: the large-scale structure of Ly$\alpha$ emitters and IGM transmission in the COSMOS field at $z\sim 5$
• Gas properties as a function of environment in the proto-supercluster Hyperion at z ~ 2.45
• Quantifying the Impact of Incompleteness on Identifying and Interpreting Galaxy Protocluster Populations with the TNG-Cluster Simulation
• LATIS: A Sample of IGM-selected Protoclusters and Protogroups at $z\sim 2.5$
• Introducing cosmosTNG: simulating galaxy formation with constrained realizations of the COSMOS field
• An Optimized Ly$\alpha$ Forest Inversion Tool Based on a Quantitative Comparison of Existing Reconstruction Methods
• Improving photometric redshifts with Ly$\alpha$ tomography
• LATIS: Comparing Galaxy and IGM Tomography Maps as Tracers of Large-scale Structure and Protoclusters at $z\sim 2.5$
• The HST-Hyperion Survey: Companion Fraction and Overdensity in a z ~ 2.5 Proto-supercluster
• Cosmological-Scale Lyman-alpha Forest Absorption Around Galaxies and AGN Probed with the HETDEX and SDSS Spectroscopic Data
• Spectroscopic confirmation of the galaxy clusters CARLA J0950+2743 at z=2.363, and CARLA-Ser J0950+2743 at z=2.243