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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731691.0, MPI für Astronomie / Publikationen_mpia
Comparing [C II] , HI, and CO dynamics of nearby galaxies
Authors:de Blok, W. J. G.; Walter, F.; Smith, J.-D.; Herrera-Camus, R.; Bolatto, A. D.; Requena-Torres, M. A.; Crocker, A. F.; Croxall, K. V.; Kennicutt, R. C.; Koda, J.; Armus, L.; Boquien, M.; Dale, D.; Kreckel, K.; Meidt, S.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:The Astronomical Journal
Issue / Number:2
Start Page:id. 51 (10 pp)
Audience:Not Specified
Abstract / Description:The H i and CO components of the interstellar medium (ISM) are usually used to derive the dynamical mass {M}{{dyn}} of nearby galaxies. Both components become too faint to be used as a tracer in observations of high-redshift galaxies. In those cases, the 158 μm line of atomic carbon ([C ii]) may be the only way to derive {M}{{dyn}}. As the distribution and kinematics of the ISM tracer affects the determination of {M}{{dyn}}, it is important to quantify the relative distributions of H i, CO, and [C ii]. H i and CO are well-characterized observationally, however, for [C ii] only very few measurements exist. Here we compare observations of CO, H i, and [C ii] emission of a sample of nearby galaxies, drawn from the HERACLES, THINGS, and KINGFISH surveys. We find that within R 25, the average [C ii] exponential radial profile is slightly shallower than that of the CO, but much steeper than the H i distribution. This is also reflected in the integrated spectrum (“global profile”), where the [C ii] spectrum looks more like that of the CO than that of the H i. For one galaxy, a spectrally resolved comparison of integrated spectra was possible; other comparisons were limited by the intrinsic line-widths of the galaxies and the coarse velocity resolution of the [C ii] data. Using high-spectral-resolution SOFIA [C ii] data of a number of star forming regions in two nearby galaxies, we find that their [C ii] linewidths agree better with those of the CO than the H i. As the radial extent of a given ISM tracer is a key input in deriving {M}{{dyn}} from spatially unresolved data, we conclude that the relevant length-scale to use in determining {M}{{dyn}} based on [C ii] data, is that of the well-characterized CO distribution. This length scale is similar to that of the optical disk.
Free Keywords:galaxies: fundamental parameters; galaxies: ISM; galaxies: kinematics and dynamics; radio lines: galaxies; submillimeter: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6256 %R 10.3847/0004-6256/152/2/51
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