Astrophys. J., 834, 5-5 (2017/January-1)
The spatially resolved [CII] cooling line deficit in galaxies.
SMITH J.D.T., CROXALL K., DRAINE B., DE LOOZE I., SANDSTROM K., ARMUS L., BEIRAO P., BOLATTO A., BOQUIEN M., BRANDL B., CROCKER A., DALE D.A., GALAMETZ M., GROVES B., HELOU G., HERRERA-CAMUS R., HUNT L., KENNICUTT R., WALTER F. and WOLFIRE M.
Abstract (from CDS):
We present [C II] 158 µm measurements from over 15,000 resolved regions within 54 nearby galaxies of the Kingfish program to investigate the so-called [C II] "line-cooling deficit" long known to occur in galaxies with different luminosities. The [C II]/TIR ratio ranges from above 1% to below 0.1% in the sample, with a mean value of 0.48 ± 0.21%. We find that the surface density of 24 µm emission dominates this trend, with [C II]/TIR dropping as νIν(24 µm) increases. Deviations from this overall decline are correlated with changes in the gas-phase metal abundance, with higher metallicity associated with deeper deficits at a fixed surface brightness. We supplement the local sample with resolved [C II] measurements from nearby luminous infrared galaxies and high-redshift sources from z = 1.8-6.4, and find that star formation rate density drives a continuous trend of deepening [C II] deficit across six orders of magnitude in Σsfr. The tightness of this correlation suggests that an approximate Σsfr can be estimated directly from global measurements of [C II]/TIR, and a relation is provided to do so. Several low-luminosity active galactic nucleus (AGN) hosts in the sample show additional and significant central suppression of [C II]/TIR, but these deficit enhancements occur not in those AGNs with the highest X-ray luminosities, but instead those with the highest central starlight intensities. Taken together, these results demonstrate that the [C II] line-cooling line deficit in galaxies likely arises from local physical phenomena in interstellar gas.
© 2016. The American Astronomical Society. All rights reserved.
dust, extinction - galaxies: ISM - infrared: galaxies - techniques: spectroscopic - techniques: spectroscopic
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