Behind the dust veil : A panchromatic view of an optically dark galaxy at z = 4.82
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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10
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Astronomy & Astrophysics, Volume 693, pp. 1-10
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 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.Description
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Sillassen, N B, Jin, S, Magdis, G E, Hodge, J, Gobat, R, Daddi, E, Knudsen, K, Finoguenov, A, Schinnerer, E, Wang, W H, Gao, Z K, Weaver, J R, Algera, H, Andika, I T, Brinch, M, Chen, C C, Cochrane, R, Enia, A, Faisst, A, Gillman, S, Gomez-Guijarro, C, Gozaliasl, G, Hayward, C, Kokorev, V, Merchant, M, Rizzo, F, Talia, M, Valentino, F, Blánquez-Sesé, D, Koekemoer, A M, Magnelli, B, Rich, M & Shuntov, M 2025, 'Behind the dust veil : A panchromatic view of an optically dark galaxy at z = 4.82', Astronomy & Astrophysics, vol. 693, A309, pp. 1-10. https://doi.org/10.1051/0004-6361/202452932