The Properties of the Interstellar Medium of Galaxies across Time as Traced by the Neutral Atomic Carbon [CI]
Abstract
We report Atacama Large Millimeter Array observations of the neutral atomic carbon transitions [C I] and multiple CO lines in a sample of similar to 30 main-sequence galaxies at z similar to 1, including novel information on [C I](P-3(2)-P-3(1)) and CO (7-6) for 7 of such normal objects. We complement our observations with a collection of >200 galaxies with coverage of similar transitions, spanning the z = 0-4 redshift interval and a variety of ambient conditions from local to high-redshift starbursts. We find systematic variations in the [C I]/IR and [C I]/high-J(upper) (J(upper) = 7) CO luminosity ratios among the various samples. We interpret these differences as increased dense molecular gas fractions and star formation efficiencies in the strongest high-redshift starbursts with respect to normal main-sequence galaxies. We further report constant L[C I]3P2 - 3P1'/L[C I]3P1 - 3P0' ratios across the galaxy populations and redshifts, suggesting that gas temperatures T-exc traced by [C I] do not strongly vary. We find only a mild correlation with T-dust and that, generally, T-exc less than or similar to T-dust. We fit the line ratios with classical photodissociation region models, retrieving consistently larger densities and intensities of the UV radiation fields in submillimeter galaxies than in main-sequence and local objects. However, these simple models fall short in representing the complexity of a multiphase interstellar medium and should be treated with caution. Finally, we compare our observations with the Santa Cruz semi-analytical model of galaxy evolution, recently extended to simulate submillimeter emission. While we confirm the success in reproducing the CO lines, we find systematically larger [C I] luminosities at fixed IR luminosity than predicted theoretically. This highlights the necessity of improving our understanding of the mechanisms regulating the [C I] emission on galactic scales. We release our data compilation to the community.
Más información
Título según WOS: | The Properties of the Interstellar Medium of Galaxies across Time as Traced by the Neutral Atomic Carbon [CI] |
Título según SCOPUS: | The Properties of the Interstellar Medium of Galaxies across Time as Traced by the Neutral Atomic Carbon [C i] |
Título de la Revista: | ASTROPHYSICAL JOURNAL |
Volumen: | 890 |
Número: | 1 |
Editorial: | IOP PUBLISHING LTD |
Fecha de publicación: | 2020 |
Idioma: | English |
DOI: |
10.3847/1538-4357/ab6603 |
Notas: | ISI, SCOPUS |