A galaxy group candidate at z~3.7 in the COSMOS field

Abstract

We report a galaxy group candidate HPC1001 at $z\approx 3.7$ in the COSMOS field. This structure was selected as a high galaxy overdensity at $z>3$ in the COSMOS2020 catalog. It contains ten candidate members, of which eight are assembled in a $10^{\prime \prime }\times 10^{\prime \prime }$ area with the highest sky density among known protoclusters and groups at $z>3$. Four out of ten sources were also detected at 1.2 mm with Atacama Large Millimeter Array continuum observations. Photometric redshifts, measured by four independent methods, fall within a narrow range of $3.5<z<3.9$ and with a weighted average of $z=3.65\pm 0.07$. The integrated far-IR-to-radio spectral energy distribution yields a total UV and IR star formation rate $\mathrm{SFR}\approx 900M_{\odot }y{r}^{-1}$. We also estimated a halo mass of $\sim 10^{13}{M}_{\odot }$ for the structure, which at this redshift is consistent with potential cold gas inflow. Remarkably, the most massive member has a specific star formation rate and dust to stellar mass ratio of $M_{\mathrm{dust}}/M_{\ast }$ that are both significantly lower than that of star-forming galaxies at this redshift, suggesting that HPC1001 could be a $z\approx 3.7$ galaxy group in maturing phase. If confirmed, this would be the earliest structure in maturing phase to date, and an ideal laboratory to study the formation of the earliest quiescent galaxies as well as cold gas accretion in dense environments.

A&A Letter in press

References in corpus (19)

• EAZY: A Fast, Public Photometric Redshift Code
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• COSMOS2020: A panchromatic view of the Universe to $z\sim 10$ from two complementary catalogs
• A massive proto-cluster of galaxies at a redshift of z {\approx} 5.3
• An excess of dusty starbursts related to the Spiderweb galaxy
• The East Asian Observatory SCUBA--2 survey of the COSMOS field: unveiling 1147 bright sub-millimeter sources across 2.6 square degrees
• COSMOS2020: The cosmic evolution of the stellar-to-halo mass relation for central and satellite galaxies up to z~5
• Confirming Herschel candidate protoclusters from ALMA/VLA CO observations
• Spectroscopic confirmation of a mature galaxy cluster at redshift two
• The Interstellar Medium of Quiescent Galaxies and its Evolution With Time
• Evidence for Cold-stream to Hot-accretion Transition as Traced by Lyα Emission from Groups and Clusters at 2 < z < 3.3
• COALAS: I. ATCA CO(1-0) survey and luminosity function in the Spiderweb protocluster at z=2.16
• The Evolving Interstellar Medium of Star-Forming Galaxies, as traced by $\text{Stardust}$
• Predicted future fate of COSMOS galaxy protoclusters over 11 Gyr with constrained simulations
• An ancient massive quiescent galaxy found in a gas-rich z ~ 3 group
• Radio selection of the most distant galaxy clusters
• Early Science with the Large Millimeter Telescope: Constraining the Gas Fraction of a Compact Quiescent Galaxy at z=1.883
• Optimizing high redshift galaxy surveys for environmental information
• The Nature of 500 Micron Risers II: Sub-mm Faint Dusty Star Forming Galaxies

Cited by in corpus (8)

• COSMOS2020: Discovery of a protocluster of massive quiescent galaxies at $z=2.77$
• Cosmic Vine: A z=3.44 large-scale structure hosting massive quiescent galaxies
• $JWST$ Insight Into a Lensed $HST$-dark Galaxy and its Quiescent Companion at $z=2.58$
• Massive galaxy formation caught in action at z~5 with JWST
• NOEMA formIng Cluster survEy (NICE): Characterizing eight massive galaxy groups at $1.5<z<4$ in the COSMOS field
• Revealing the hidden cosmic feast: A z=4.3 galaxy group hosting two optically dark, efficiently star-forming galaxies
• Cosmic Vine: High abundance of massive galaxies and dark matter halos in a forming cluster at z=3.44
• Noema formIng Cluster survEy (NICE): A Census of Star Formation and Cold Gas Properties in Massive protoclusters at 1.5<z<4