Clumpy star formation and an obscured nuclear starburst in the luminous dusty z = 4 galaxy GN20 seen by MIRI/JWST

Autor(en): A. Bik, J. Alvarez-Marquez, L. Colina, A. Crespo Gomez, F. Peissker, F. Walter, L. A. Boogaard, G. AOstlin, T. R. Greve, G. Wright, A. Alonso-Herrero, K. I. Caputi, L. Costantin, A. Eckart, S. Gillman, J. Hjorth, E. Iani, I. Jermann, A. Labiano, D. Langeroodi, J. Melinder, P. G. Perez-Gonzalez, J. P. Pye, P. Rinaldi, T. Tikkanen, P. Van Der Werf, M. Güdel, Th Henning, P. O. Lagage, T. Ray, E. F. Van Dishoeck
Abstrakt: Dusty star-forming galaxies emit most of their light at far-infrared to millimeter wavelengths as their star formation is highly obscured. Far-infrared and millimeter observations have revealed their dust, neutral and molecular gas properties. The sensitivity of JWST at rest-frame optical and near-infrared wavelengths now allows the study of the stellar and ionized gas content. We investigate the spatially resolved distribution and kinematics of the ionized gas in GN20, a dusty star-forming galaxy at z= 4.0548. We present deep MIRI/MRS integral field spectroscopy of the near-infrared rest-frame emission of GN20. We detect spatially resolved Paα, out to a radius of 6 kpc, distributed in a clumpy morphology. The star formation rate derived from Paα (144 ± 9 M yr1) is only 7.7 ± 0.5% of the infrared star formation rate (1860 ± 90 M yr1). We attribute this to very high extinction (AV = 17.2 ± 0.4 mag, or AV, mixed = 44 ± 3 mag), especially in the nucleus of GN20, where only faint Paα is detected, suggesting a deeply buried starburst. We identify four, spatially unresolved, clumps in the Paα emission. Based on the double peaked Paα profile, we find that each clump consists of at least two sub-clumps. We find mass upper limits consistent with them being formed in a gravitationally unstable gaseous disk. The ultraviolet bright region of GN20 does not have any detected Paα emission, suggesting an age of more than 10 Myr for this region of the galaxy. From the rotation profile of Paα, we conclude that the gas kinematics are rotationally dominated and the vrot/I m = 3.8 ± 1.4 is similar to low-redshift luminous infrared galaxies. From the Paα kinematics, we cannot distinguish between a rotational profile of a large disk and a late stage merger mimicking a disk. We speculate that GN20 is in the late stage of a major merger, where the clumps in a large gas-rich disk are created by the major merger, while the central starburst is driven by the merger event.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): Oskar Klein Centre, European Space Astronomy Centre (ESA), Universität zu Köln, Max-Planck-Institut für Astronomie, Technical University of Denmark (DTU), University of Copenhagen, University College London, The Royal Observatory, Edinburgh, University of Groningen, University of Leicester, Leiden University, Eidgenössische Technische Hochschule Zürich, Université Paris Saclay, Dublin Institute for Advanced Studies
Journal: Astronomy and Astrophysics
Band: 686
Anzahl der Seiten: 14
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/202348845
Publikationsdatum: 06-2024
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/009342b3-afcf-4bcd-84fd-5740bd4fd2b6

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