Dust continuum, CO, and [C I] 1-0 lines: self-consistent H2 mass estimates and the possibility of globally CO-dark galaxies at $z = 0.35$

L. Dunne; S. J. Maddox; C. Vlahakis; H. L. Gomez

doi:10.1093/mnras/staa3526

paper

Dust continuum, CO, and [C I] 1-0 lines: self-consistent H2 mass estimates and the possibility of globally CO-dark galaxies at $z = 0.35$

arXiv:2111.09067 · doi:10.1093/mnras/staa3526

Abstract

We present ALMA observations of a small but statistically complete sample of twelve 250 micron selected galaxies at $z = 0.35$ designed to measure their dust submillimeter continuum emission as well as their CO(1-0) and atomic carbon [CI](3P1-3P0) spectral lines. This is the first sample of galaxies with global measures of all three $H_{2}$ -mass tracers and which show star formation rates (4-26 Msun yr $^{- 1}$ ) and infra-red luminosities ( $1 - 6 \times 1 0^{11}$ Lsun) typical of star forming galaxies in their era. We find a surprising diversity of morphology and kinematic structure; one-third of the sample have evidence for interaction with nearby smaller galaxies, several sources have disjoint dust and gas morphology. Moreover two galaxies have very high $L_{C I} / L_{C O}$ ratios for their global molecular gas reservoirs; if confirmed, such extreme intensity ratios in a sample of dust selected, massive star forming galaxies presents a challenge to our understanding of ISM. Finally, we use the emission of the three molecular gas tracers, to determine the carbon abundance, $X_{c i}$ , and CO- $H_{2}$ conversion $α_{co}$ in our sample, using a weak prior that the gas-to-dust ratio is similar to that of the Milky Way for these massive and metal rich galaxies. Using a likelihood method which simultaneously uses all three gas tracer measurements, we find mean values and errors on the mean of $α_{co} = 3.0 \pm 0.5 Msun (K km s^{- 1} p c^{2})^{- 1}$ and $X_{c i} = 1.6 \pm 0.1 \times 1 0^{- 5}$ (or $α_{c i} = 18.8 K k m s^{- 1} p c^{2} (M s u n)^{- 1}$ ) and $δ_{G D R} = 128 \pm 16$ (or $α_{850} = 5.9 \times 1 0^{12} W H z^{- 1} Msu n^{- 1}$ ), where our starting assumption is that these metal rich galaxies have an average gas-to-dust ratio similar to that of the Milky Way centered on $δ_{G D R} = 135$ .

arXiv comment34 pages, published in MNRAS

Dust continuum, CO, and [C I] 1-0 lines: self-consistent H2 mass estimates and the possibility of globally CO-dark galaxies at $z = 0.35$

Abstract

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Dust continuum, CO, and [C I] 1-0 lines: self-consistent H2 mass estimates and the possibility of globally CO-dark galaxies at z=0.35

Abstract

References in corpus (105)

Cited by in corpus (27)

Dust continuum, CO, and [C I] 1-0 lines: self-consistent H2 mass estimates and the possibility of globally CO-dark galaxies at $z = 0.35$