COSMOS2020: Discovery of a protocluster of massive quiescent galaxies at $z=2.77$

Abstract

Protoclusters of galaxies have been found in the last quarter century. However, most of them have been found through the overdensity of star-forming galaxies, and there had been no known structures identified by multiple spectroscopically confirmed quiescent galaxies at $z>2.5$. In this letter, we report the discovery of an overdense structure of massive quiescent galaxies with the spectroscopic redshift $z=2.77$ in the COSMOS field, QO-1000. We first photometrically identify this structure as a $4.2\sigma$ overdensity with 14 quiescent galaxies in $7\times 4\mathrm{pMp}{\mathrm{c}}^2$ from the COSMOS2020 catalog. We then securely confirm the spectroscopic redshifts of 4 quiescent galaxies by detecting multiple Balmer absorption lines with Keck/MOSFIRE. All the spectroscopically confirmed members are massive ($\log (M_{\star }/M_{\odot })>11.0$) and located in a narrow redshift range ($2.76<z<2.79$). Moreover, three of them are in the $1\times 1\mathrm{pMp}{\mathrm{c}}^2$ in the transverse direction at the same redshift ($z=2.760-2.763$). Such a concentration of four spectroscopically confirmed quiescent galaxies implies that QO-1000 is $>68$ times denser than in the general field. In addition, we confirm that they form a red sequence in the $J-K_s$ color. This structure's halo mass is estimated as $\log (M_{\mathrm{halo}}/M_{\odot })>13.2$ from their stellar mass. Similar structures found in the IllustrisTNG simulation are expected to evolve into massive galaxy clusters with $\log (M_{\mathrm{halo}}/M_{\odot })\ge 14.8$ at $z=0$. These results suggest that QO-1000 is a more mature protocluster than the other known protoclusters. It is likely in a transition phase between the star-forming protoclusters and the quenched galaxy clusters.

11 pages, 4 figures, 1 table, accepted for publication in ApJL

References in corpus (32)

• Array Programming with NumPy
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• EAZY: A Fast, Public Photometric Redshift Code
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• COSMOS2020: A panchromatic view of the Universe to $z\sim 10$ from two complementary catalogs
• The First Appearance of the Red Sequence of Galaxies in Proto-Clusters at 2<~z<~3
• A surprising abundance of massive quiescent galaxies at 3 < z < 5 in the first data from JWST CEERS
• Photometric Redshift with Bayesian Priors on Physical Properties of Galaxies
• The VLA-COSMOS 3 GHz Large Project: Evolution of specific star formation rates out to $z\sim 5$
• The space density of luminous dusty star-forming galaxies at $z>4$: SCUBA-2 and LABOCA imaging of ultrared galaxies from $Herschel$-ATLAS
• The Massive Ancient Galaxies At $z>3$ NEar-infrared (MAGAZ3NE) Survey: Confirmation of Extremely Rapid Star-Formation and Quenching Timescales for Massive Galaxies in the Early Universe
• MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. I - Evolution of Structural and Dynamical Properties
• An Extremely Massive Quiescent Galaxy at $z=3.493$: Evidence of Insufficiently Rapid Quenching Mechanisms in Theoretical Models
• Automated Mining of the ALMA Archive in the COSMOS Field (A3COSMOS): I. Robust ALMA Continuum Photometry Catalogs and Stellar Mass and Star Formation Properties for ~700 Galaxies at z=0.5-6
• Spectroscopic Confirmation of a Protocluster at $z=3.37$ with a High Fraction of Quiescent Galaxies
• COSMOS2020: The cosmic evolution of the stellar-to-halo mass relation for central and satellite galaxies up to z~5
• Three Lyman-alpha emitting filaments converging to a massive galaxy group at z=2.91: discussing the case for cold gas infall
• The Nascent Red Sequence at z~2
• A Lyman-α protocluster at redshift 6.9
• Large Scale Structures in the CANDELS Fields: The Role of the Environment in Star Formation Activity
• The Rapid Build-up of Massive Early-type Galaxies. Supersolar Metallicity, High Velocity Dispersion and Young Age for an ETG at z=3.35
• A lensed protocluster candidate at $z=7.66$ identified in JWST observations of the galaxy cluster SMACS0723-7327
• Discovery of a Proto-cluster Associated with a Ly-$\alpha$ Blob Pair at z=2.3
• HST grism spectroscopy of z~3 massive quiescent galaxies: Approaching the metamorphosis
• COSMOS2020: Ubiquitous AGN Activity of Massive Quiescent Galaxies at $0<z<5$ Revealed by X-ray and Radio Stacking
• An ancient massive quiescent galaxy found in a gas-rich z ~ 3 group
• Optical and near-infrared observations of the SPT2349-56 proto-cluster core at z = 4.3
• Early results from GLASS-JWST. IX: First spectroscopic confirmation of low-mass quiescent galaxies at $z>2$ with NIRISS
• A galaxy group candidate at z~3.7 in the COSMOS field
• Interrelation of the environment of Ly$\alpha$ emitters and massive galaxies at $2<z<4.5$
• 3D-DASH: The Widest Near-Infrared Hubble Space Telescope Survey

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• Discovering Large-Scale Structure at $2<z<5$ in the C3VO Survey
• The COSMOS-Web deep galaxy group catalog up to $z=3.7$
• Revealing the quiescent galaxy population in the Spiderweb protocluster at z=2.16 with deep HST/WFC3 slitless spectroscopy
• COALAS III: The ATCA CO(1-0) look at the growth and death of H$\alpha$ emitters in the Spiderweb protocluster at z=2.16
• Galaxy populations of ProtoClusters in cosmological hydrodynamical simulations
• Cluster candidates with massive quiescent galaxies at $z\sim 2$
• Quenching of Galaxies at Cosmic Noon: Understanding the Effect of Environment
• Gas properties as a function of environment in the proto-supercluster Hyperion at z ~ 2.45
• Insights into environmental quenching at $z\sim 1$: an enhancement of faint, low-mass passive galaxies in clusters
• LATIS: A Sample of IGM-selected Protoclusters and Protogroups at $z\sim 2.5$
• pop-cosmos: Insights from generative modeling of a deep, infrared-selected galaxy population
• Black hole mass of a quiescent galaxy hosting a Type 1 AGN at z=2.09: Implications for black hole - galaxy co-evolution and AGN quenching at high redshift
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• The JWST Emission Line Survey (JELS): The sizes and merger fraction of star-forming galaxies during the Epoch of Reionization
• LATIS: Comparing Galaxy and IGM Tomography Maps as Tracers of Large-scale Structure and Protoclusters at $z\sim 2.5$
• Cosmic Vine: High abundance of massive galaxies and dark matter halos in a forming cluster at z=3.44
• ADF22+: a declining faint end in the far-infrared luminosity function in the SSA22 protocluster at z=3.09
• Dynamical properties and star formation history of a low-mass quenched galaxy at Cosmic Noon
• The Connection between Dusty Star-Forming Galaxies and the First Massive Quenched Galaxies