Behind the dust veil: A panchromatic view of an optically dark galaxy at z=4.82

Abstract

Optically dark dusty star-forming galaxies (DSFGs) play an essential role in massive galaxy formation at early cosmic time, however their nature remains elusive. Here we present a detailed case study of all the baryonic components of a $z=4.821$ DSFG, XS55. Selected from the ultra-deep COSMOS-XS 3GHz map with a red SCUBA-2 450$\mu$m/850$\mu$m colour, XS55 was followed up with ALMA 3mm line scans and spectroscopically confirmed to be at $z=4.821$ via detections of the CO(5-4) and [CI](1-0) lines. JWST/NIRCam imaging reveals that XS55 is a F150W-dropout with red F277W/F444W colour, and a complex morphology: a compact central component embedded in an extended structure with a likely companion. XS55 is tentatively detected in X-rays with both Chandra and XMM-Newton, suggesting an active galactic nucleus (AGN) nature. By fitting a panchromatic SED spanning NIR to radio wavelengths, we revealed that XS55 is a massive main-sequence galaxy with a stellar mass of $M_{\ast }=(5\pm 1)\times 10^{10}{\mathrm{M}}_{\odot }$ and a star formation rate of $\mathrm{SFR}=540\pm 177{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$. The dust of XS55 is optically thick in the far infrared (FIR) with a surprisingly cold dust temperature of $T_{\mathrm{dust}}=33\pm 2\mathrm{K}$, making XS55 one of the coldest DSFGs at $z>4$ known to date. This work unveils the nature of a radio-selected F150W-dropout, suggesting the existence of a population of DSFGs hosting active black holes embedded in optically thick dust.

11 pages, 7 figures, accepted in Astronomy & Astrophysics

References in corpus (46)

• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• A Dust-Obscured Massive Maximum-Starburst Galaxy at a Redshift of 6.34
• COSMOS2020: A panchromatic view of the Universe to $z\sim 10$ from two complementary catalogs
• The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• The XMM-Newton wide-field survey in the COSMOS field: I. Survey description
• Galaxy growth in a massive halo in the first billion years of cosmic history
• Dust temperature and mid-to-total infrared color distributions for star-forming galaxies at 0<z<4
• ALMA Imaging of Gas and Dust in a Galaxy Protocluster at Redshift 5.3: [CII] Emission in "Typical" Galaxies and Dusty Starbursts ~1 Billion Years after the Big Bang
• An Atlas of Color-selected Quiescent Galaxies at $z>3$ in Public $JWST$ Fields
• Molecular outflows in local galaxies: Method comparison and a role of intermittent AGN driving
• Normal, Dust-Obscured Galaxies in the Epoch of Reionization
• CEERS Key Paper V: A triality on the nature of HST-dark galaxies
• The infrared-radio correlation of star-forming galaxies is strongly M${}_{\star }$-dependent but nearly redshift-invariant since z$\sim$4
• The East Asian Observatory SCUBA--2 survey of the COSMOS field: unveiling 1147 bright sub-millimeter sources across 2.6 square degrees
• Unveiling the Nature of Infrared Bright, Optically Dark Galaxies with Early JWST Data
• An ALMA/NOEMA survey of the molecular gas properties of high-redshift star-forming galaxies
• ALMA Characterises the Dust Temperature of z ~ 5.5 Star-Forming Galaxies
• Predictions for the spatial distribution of the dust continuum emission in 1<z<5 star-forming galaxies
• GOODS-ALMA 2.0: Source catalog, number counts, and prevailing compact sizes in 1.1 mm galaxies
• Dual constraints with ALMA: new [O III] 88 $\mu$m and dust-continuum observations reveal the ISM conditions of luminous LBGs at $z\sim 7$
• Dust, CO and [CI]: Cross-calibration of molecular gas mass tracers in metal-rich galaxies across cosmic time
• Physical Characterization of an Unlensed Dusty Star-Forming Galaxy at $z=5.85$
• Mapping Obscuration to Reionization with ALMA (MORA): 2mm Efficiently Selects the Highest-Redshift Obscured Galaxies
• An ALMA survey of the S2CLS UDS field: Optically invisible submillimetre galaxies
• Illuminating the dark side of cosmic star formation two billion years after the Big Bang
• Knocking on giants' doors: I. The evolution of the dust-to-stellar mass ratio in distant dusty galaxies
• The ALMA-ALPAKA survey I: high-resolution CO and [CI] kinematics of star-forming galaxies at z = 0.5-3.5
• A new estimate of the cosmic star formation density from a radio-selected sample, and the contribution of $H$-dark galaxies at $z\ge 3$
• A Multi-wavelength Analysis of the Faint Radio Sky (COSMOS-XS): the Nature of the Ultra-faint Radio Population
• An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS field (AS2COSPEC): Survey Description and First Results
• An Ultra-deep Multi-band VLA Survey of the Faint Radio Sky (COSMOS-XS): Source Catalog and Number Counts
• The Evolving Interstellar Medium of Star-Forming Galaxies, as traced by $\text{Stardust}$
• The hidden side of cosmic star formation at z > 3: Bridging optically-dark and Lyman break galaxies with GOODS-ALMA
• Unveiling the hidden universe with JWST: The contribution of dust-obscured galaxies to the stellar mass function at $z\sim 3-8$
• Direct measurement of the [CI] luminosity to molecular gas mass conversion factor in high-redshift star-forming galaxies
• JWST CEERS probes the role of stellar mass and morphology in obscuring galaxies
• $JWST$ Insight Into a Lensed $HST$-dark Galaxy and its Quiescent Companion at $z=2.58$
• A census of optically dark massive galaxies in the early Universe from magnification by lensing galaxy clusters
• A photo-z cautionary tale: Redshift confirmation of COSBO-7 at z=2.625
• Illuminating the Dark Side of Cosmic Star Formation III: Building the largest homogeneous sample of Radio-Selected Dusty Star-Forming Galaxies in COSMOS with PhoEBO
• Noema formIng Cluster survEy (NICE): Discovery of a starbursting galaxy group with a radio-luminous core at z=3.95
• NOEMA formIng Cluster survEy (NICE): Characterizing eight massive galaxy groups at $1.5<z<4$ in the COSMOS field
• X-ray luminosity-star formation rate scaling relation: Constraints from the eROSITA Final Equatorial Depth Survey (eFEDS)
• Estimating Dust Temperature and Far-IR Luminosity of High-Redshift Galaxies using ALMA Single-Band Continuum Observations
• SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES). V. Confusion-limited Submillimeter Galaxy Number Counts at 450 $\mu$m and Data Release for the COSMOS Field

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• When relics were made: vigorous stellar rotation and low dark matter content in the massive ultra-compact galaxy GS-9209 at z=4.66
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