Rybak, M;
Hodge, JA;
Greve, TR;
Riechers, D;
Lamperti, I;
van Marrewijk, J;
Walter, F;
... van der Werf, PP; + view all
(2022)
PRUSSIC: I. A JVLA survey of HCN, HCO+, and HNC (1–0) emission in z ∼ 3 dusty galaxies: Low dense-gas fractions in high-redshift star-forming galaxies.
Astronomy & Astrophysics
, 667
, Article A70. 10.1051/0004-6361/202243894.
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Abstract
Dusty star-forming galaxies (DSFGs) at redshift z ≥ 1 are among the most vigorously star-forming galaxies in the Universe. However, their dense (≥105 cm−3) gas phase – typically traced by HCN(1–0) – remains almost entirely unexplored: only two DSFGs have been detected in HCN(1–0) to date. We present the results of a Karl G. Jansky Very Large Array survey of the J = 1–0 transition of HCN, HCO+, and HNC(1–0) in six strongly lensed DSFGs at z = 2.5 − 3.3, effectively doubling the number of DSFGs with deep observations of these lines. We detect HCN(1–0) emission in one source (J1202+5354, 4.6 σ), with a tentative HCO+(1–0) detection in another (J1609+6045, 3.3σ). Spectral stacking yields strict upper limits on the HCN/FIR (≤3.6 × 10−4) and HCN/CO(1–0) ratios (≤0.045). The inferred HCN/FIR ratios (a proxy for the star-formation efficiency) are consistent with those in z ∼ 0 far-infrared-luminous starbursts. However, the HCN/CO ratios – a proxy for the dense-gas fraction – are a factor of a few lower than suggested by the two previous DSFG detections. Our results imply that most DSFGs have low dense-gas fractions. A comparison with theoretical models of star-forming galaxies indicates that the bulk of gas in DSFGs is at lower densities (≈102 cm−3), similar to ‘normal’ star-forming galaxies, rather than ultraluminous starbursts.
| Type: | Article |
|---|---|
| Title: | PRUSSIC: I. A JVLA survey of HCN, HCO+, and HNC (1–0) emission in z ∼ 3 dusty galaxies: Low dense-gas fractions in high-redshift star-forming galaxies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1051/0004-6361/202243894 |
| Publisher version: | https://doi.org/10.1051/0004-6361/202243894 |
| Language: | English |
| Additional information: | Copyright © M. Rybak et al. 2022. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | galaxies: high-redshift; galaxies: ISM; galaxies: star formation; submillimeter: general; radio lines: galaxies |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10160790 |
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