Behind the dust veil: A panchromatic view of an optically dark galaxy at z = 4.82
Artikel i vetenskaplig tidskrift, 2025

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 3 GHz map with a red SCUBA-2 450 μm/850 μm colour, XS55 was followed up with ALMA 3 mm 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 drop-out with a 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 nature. By fitting a panchromatic spectral energy distribution spanning from near-infrared to radio wavelengths, we reveal that XS55 is a massive main-sequence galaxy with a stellar mass of M∗ = (5 ± 1)×1010 M⊙ and a star formation rate of SFR = 540 ± 177 M⊙ yr- 1. The dust of XS55 is optically thick in the far-infrared with a surprisingly cold dust temperature of Tdust = 33 ± 2 K, making XS55 one of the coldest DSFGs at z > 4 known to date. This work unveils the nature of a radio-selected F150W drop-out, suggesting the existence of a population of DSFGs hosting active black holes embedded in optically thick dust.

Galaxies: general

Galaxies: ISM

Galaxies: active

Författare

Nikolaj B. Sillassen

Danmarks Tekniske Universitet (DTU)

Cosmic Dawn Center (DAWN)

S. Jin

Danmarks Tekniske Universitet (DTU)

Cosmic Dawn Center (DAWN)

Georgios E. Magdis

Niels Bohr Institute

Danmarks Tekniske Universitet (DTU)

Cosmic Dawn Center (DAWN)

J. Hodge

Universiteit Leiden

Raphael Gobat

Pontificia Universidad Católica de Valparaíso

Emanuele Daddi

Université Paris-Saclay

Kirsten Knudsen

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Alexis Finoguenov

Helsingin Yliopisto

E. Schinnerer

Max-Planck-Gesellschaft

Wei Hao Wang

Academia Sinica

Zhen Kai Gao

Academia Sinica

J. R. Weaver

University of Massachusetts

H. Algera

National Astronomical Observatory of Japan

Academia Sinica

Hiroshima University

Irham T. Andika

Max-Planck-Gesellschaft

Technische Universität München

Malte Brinch

Universidad de Valparaíso

C. C. Chen

Academia Sinica

R. Cochrane

Columbia University

University of Edinburgh

A. F.M. Enia

Istituto nazionale di astrofisica (INAF)

Universita di Bologna

A. Faisst

California Institute of Technology (Caltech)

S. Gillman

Cosmic Dawn Center (DAWN)

Danmarks Tekniske Universitet (DTU)

Carlos Gomez-Guijarro

Université Paris-Saclay

Ghassem Gozaliasl

Helsingin Yliopisto

Aalto-Yliopisto

Christopher C. Hayward

Flatiron Institute

V. Kokorev

The University of Texas at Austin

Maya Merchant

Cosmic Dawn Center (DAWN)

Niels Bohr Institute

Francesca Rizzo

Rijksuniversiteit Groningen

Margherita Talia

Istituto nazionale di astrofisica (INAF)

Universita di Bologna

F. Valentino

Cosmic Dawn Center (DAWN)

Danmarks Tekniske Universitet (DTU)

David Blánquez-Sesé

Cosmic Dawn Center (DAWN)

Danmarks Tekniske Universitet (DTU)

Anton M. Koekemoer

Space Telescope Science Institute (STScI)

Benjamin Magnelli

Université Paris-Saclay

R. Michael Rich

University of California

Marko Shuntov

Cosmic Dawn Center (DAWN)

Niels Bohr Institute

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 693 A309

The Origin and Fate of Dust in Our Universe

Knut och Alice Wallenbergs Stiftelse (KAW 2019.0443), 2020-06-01 -- 2023-05-31.

Knut och Alice Wallenbergs Stiftelse (KAW 2020.0081), 2021-07-01 -- 2026-06-30.

Ämneskategorier (SSIF 2025)

Annan fysik

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/202452932

Mer information

Senast uppdaterat

2025-02-19