[C i](1–0) and [C i](2–1) in Resolved Local Galaxies* Journal Articles uri icon

  • Overview
  • Research
  • Identity
  • Additional Document Info
  • View All


  • 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 to (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.


  • Crocker, Alison F
  • Pellegrini, Eric
  • Smith, J-DT
  • 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
  • Werf, Paul van der

publication date

  • December 10, 2019