[C I](1-0) and [C I](2-1) in Resolved Local Galaxies

December 2019 • 2019ApJ...887..105C

Authors • Crocker, Alison F. • Pellegrini, Eric • Smith, J. -D. T. • Draine, Bruce T. • Wilson, Christine D. • Wolfire, Mark • Armus, Lee • Brinks, Elias • Dale, Daniel A. • Groves, Brent • Herrera-Camus, Rodrigo • Hunt, Leslie K. • Kennicutt, Robert C. • Murphy, Eric J. • Sandstrom, Karin • Schinnerer, Eva • Rigopoulou, Dimitra • Rosolowsky, Erik • van der Werf, Paul

Abstract • We present resolved [C I] line intensities of 18 nearby galaxies observed with the SPIRE FTS spectrometer on the Herschel Space Observatory. We use these data along with resolved CO line intensities from J _up = 1 to 7 to interpret what phase of the interstellar medium the [C I] lines trace within typical local galaxies. A tight, linear relation is found between the intensities of the CO(4-3) and [C I](2-1) lines; we hypothesize this is due to the similar upper level temperature of these two lines. We modeled the [C I] and CO line emission using large-velocity gradient models combined with an empirical template. According to this modeling, the [C I](1-0) line is clearly dominated by the low-excitation component. We determine [C I] to molecular mass conversion factors for both the [C I](1-0) and [C I](2-1) lines, with mean values of α _{[C I](1-0)} = 7.3 M _⊙ K^-1 km^-1 s pc^-2 and α _{[C I](2-1)} = 34 M _⊙ K^-1 km^-1 s pc^-2 with logarithmic root-mean-square spreads of 0.20 and 0.32 dex, respectively. The similar spread of {α }_[{{C}{{I}}](1{--}0)} to {α }_CO} (derived using the CO(2-1) line) suggests that [C I](1-0) may be just as good a tracer of cold molecular gas as CO(2-1) in galaxies of this type. On the other hand, the wider spread of α _{[C I](2-1)} and the tight relation found between [C I](2-1) and CO(4-3) suggest that much of the [C I](2-1) emission may originate in warmer molecular gas.

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Links

• PREPRINT http://arxiv.org/abs/2001.05047
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2019ApJ...887..105C
• ELECTR https://doi.org/10.3847%2F1538-4357%2Fab4196
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2019ApJ...887..105C
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ab4196/pdf
• PDF https://stacks.iop.org/0004-637X/887/105/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/887/105
• DATA http://archives.esac.esa.int/hsa/whsa/?ACTION=PUBLICATION&ID=2019ApJ...887..105C