Oteo, I;
Zhang, ZY;
Yang, C;
Ivison, RJ;
Omont, A;
Bremer, M;
Bussmann, S;
... Werf, PVD; + view all
(2017)
High Dense Gas Fraction in Intensely Star-forming Dusty Galaxies.
Astrophysical Journal
, 850
(2)
, Article 170. 10.3847/1538-4357/aa8ee3.
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Abstract
We present ALMA J = 3-2 and VLA J = 1-0 observations of the dense molecular gas tracers HCN, HCO+, and HNC in two lensed, high-redshift starbursts selected from the Herschel-ATLAS survey: H-ATLAS J090740.0-004200 (SDP.9, z spec = 1.575) and H-ATLAS J091043.1-000321 (SDP.11, z spec = 1.786). In SDP.9 we have detected all J = 3-2 transitions and also HCN(1-0) and HCO+(1-0). In SDP.11 we have detected HCN(3-2) and HCO+(3-2). The amplification factors for both galaxies have been determined from subarcsecond-resolution CO and dust emission observations carried out with NOEMA and the SMA. The HNC(1-0)/HCN(1-0) line ratio in SDP.9 suggests the presence of photon-dominated regions, as happens in most local (U)LIRGs. The CO, HCN, and HCO+ spectral line energy distribution (SLEDs) of SDP.9 are compatible to those found for many local, IR-bright galaxies, indicating that the molecular gas in local and high-redshift dusty starbursts can have similar excitation conditions. We obtain that the correlation between total IR (L IR ) and dense line (L dense ) luminosity in SDP.9 and SDP.11 and local star-forming galaxies can be represented by a single relation. We argue that the scatter of the L IR -L dense correlation, together with the lack of sensitive dense molecular gas tracer observations for a homogeneous sample of high-redshift galaxies, prevents us from distinguishing differential trends with redshift. Our results suggest that the intense star formation found in some high-redshift, dusty, luminous starbursts is associated with more massive dense molecular gas reservoirs and higher dense molecular gas fractions.
Type: | Article |
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Title: | High Dense Gas Fraction in Intensely Star-forming Dusty Galaxies |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.3847/1538-4357/aa8ee3 |
Publisher version: | https://doi.org/10.3847/1538-4357/aa8ee3 |
Language: | English |
Additional information: | This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
Keywords: | galaxies: high-redshift; galaxies: ISM; galaxies: starburst; galaxies: star formation |
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 |
URI: | https://discovery.ucl.ac.uk/id/eprint/10041321 |
1. | United States | 5 |
2. | China | 1 |
3. | United Kingdom | 1 |
4. | Germany | 1 |
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