aa37217-19.pdf (2.49 MB)
Deceptively cold dust in the massive starburst galaxy GN20 at z ~4
journal contribution
posted on 2023-06-09, 22:05 authored by Isabella Cortzen, Georgios E Magdis, Francesco Valentino, Emanuele Daddi, Daizhong Liu, Dimitra Rigopoulou, Mark Sargent, Dominik Riechers, Diane Cormier, Jacqueline A Hodge, Fabian Walter, David Elbaz, Matthieu Béthermin, Thomas R Greve, Vasily Kokorev, Sune ToftWe present new observations, carried out with IRAM NOEMA, of the atomic neutral carbon transitions [C» I](3P1-3P0) at 492 GHz and [C» I](3P2-3P1) at 809 GHz of GN20, a well-studied star-bursting galaxy at z = 4.05. The high luminosity line ratio [C» I](3P2-3P1) /[C» I](3P1-3P0) implies an excitation temperature of 48+14-9 K, which is significantly higher than the apparent dust temperature of Td = 33 ± 2 K (ß = 1.9) derived under the common assumption of an optically thin far-infrared dust emission, but fully consistent with Td = 52 ± 5 K of a general opacity model where the optical depth (t) reaches unity at a wavelength of ?0 = 170 ± 23 µm. Moreover, the general opacity solution returns a factor of ~2× lower dust mass and, hence, a lower molecular gas mass for a fixed gas-to-dust ratio, than with the optically thin dust model. The derived properties of GN20 thus provide an appealing solution to the puzzling discovery of starbursts appearing colder than main-sequence galaxies above z > 2.5, in addition to a lower dust-to-stellar mass ratio that approaches the physical value predicted for starburst galaxies.
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- Published
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- Published version
Journal
Astronomy and AstrophysicsISSN
0004-6361Publisher
EDP SciencesExternal DOI
Issue
L14Volume
634Page range
1-6Department affiliated with
- Physics and Astronomy Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2020-11-09First Open Access (FOA) Date
2020-11-09First Compliant Deposit (FCD) Date
2020-11-09Usage metrics
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