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Journal Articles The Astrophysical Journal Year : 2017

High Dense Gas Fraction in Intensely Star-forming Dusty Galaxies

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I. Oteo
  • Function : Author
Z. -Y. Zhang
  • Function : Author
R. J. Ivison
  • Function : Author
M. Bremer
  • Function : Author
S. Bussmann
  • Function : Author
A. Cooray
  • Function : Author
P. Cox
  • Function : Author
H. Dannerbauer
  • Function : Author
L. Dunne
  • Function : Author
S. Eales
  • Function : Author
C. Furlanetto
  • Function : Author
Y. Gao
  • Function : Author
T. R. Greve
  • Function : Author
H. Nayyeri
  • Function : Author
M. Negrello
  • Function : Author
R. Neri
  • Function : Author
D. Riechers
  • Function : Author
R. Tunnard
  • Function : Author
J. Wagg
  • Function : Author
P. van der Werf
  • Function : Author

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.

Dates and versions

insu-03744563 , version 1 (03-08-2022)

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I. Oteo, Z. -Y. Zhang, C. Yang, R. J. Ivison, A. Omont, et al.. High Dense Gas Fraction in Intensely Star-forming Dusty Galaxies. The Astrophysical Journal, 2017, 850, ⟨10.3847/1538-4357/aa8ee3⟩. ⟨insu-03744563⟩
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