Unveiling dust, molecular gas, and high star-formation efficiency in extremely UV bright star-forming galaxies at z ∼ 2.1-3.6

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A90106%2F25%3A00646721" target="_blank" >RIV/67985815:90106/25:00646721 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1051/0004-6361/202451832" target="_blank" >https://doi.org/10.1051/0004-6361/202451832</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202451832" target="_blank" >10.1051/0004-6361/202451832</a>

Result language

angličtina

Original language name

Unveiling dust, molecular gas, and high star-formation efficiency in extremely UV bright star-forming galaxies at z ∼ 2.1-3.6

Original language description

We analysed the Atacama Large Millimetre/submillimetre Array (ALMA) far-infrared (FIR), 1.3 mm, dust continuum and CO emission of 12 starburst galaxies at z similar to 2.1 3.6 selected for their extreme brightness in the rest-frame UV, with absolute magnitudes of23.4 to24.7. We also analysed their Very Large Telescope (VLT) High Acuity Wide field K-band Imager (HAWK-I) H- and K-s-band images. The targeted galaxies are characterised by negligible dust attenuations with blue UV spectral slopes (-2.62 to1.84), very young stellar populations of similar to 10 Myr, and powerful starbursts with a high mean specific star-formation rate of 112 Gyr(-1), placing them similar to 1.5 dex above the main sequence at similar redshifts and stellar masses (M-stars similar to (1.5 4.6)x10(9) M-circle dot). The FIR dust continuum emission revealed in nine galaxies gives IR luminosities of (5.9 28.3)x10(11) L-circle dot, with six galaxies remaining dominated by unobscured UV star-formation rates, and high dust masses barely produced by supernovae within the 10 Myr timescale. The CO emission detected in eight galaxies leads to molecular gas masses higher than stellar masses, with the mean molecular gas mass fraction as high as 82%. The corresponding star-formation efficiencies reach greater than or similar to 40%, with amazingly short molecular gas depletion timescales between less than 13 Myr and 71 Myr. These unique properties never reported in previously studied galaxies highlight that these galaxies are likely caught at the very beginning of their stellar mass build-up and undergo a very efficient and fast conversion of gas into stars that can only result from the gas collapse within a very short free-fall time. We find that the feedback-free starburst model seems to be able to explain the formation of these galaxies. To reconcile the co-spatial FIR dust emission with the UV-bright unattenuated emission, we speculate about the presence of radiation-driven outflows that can temporarily remove dust at the location of the starburst and expel it at large distances in line with the measured high FIR effective radii (1.7 kpc to 5 kpc) in comparison to the very compact stellar radii of a few hundred parsecs.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

—

Continuities

—

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

693

Issue of the periodical within the volume

Jan.

Country of publishing house

FR - FRANCE

Number of pages

21

Pages from-to

A17

UT code for WoS article

001382923000004

EID of the result in the Scopus database

2-s2.0-105001196784