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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 731896.0, MPI für Astronomie / Publikationen_mpia
HI and CO velocity dispersions in nearby galaxies
Authors:Mogotsi, K. M.; de Blok, W. J. G.; Caldú-Primo, A.; Walter, F.; Ianjamasimanana, R.; Leroy, A. K.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:The Astronomical Journal
Volume:151
Issue / Number:1
Start Page:id. 15 (11 pp)
Audience:Not Specified
Abstract / Description:We analyze the velocity dispersions of individual H i and CO profiles in a number of nearby galaxies from the high-resolution HERACLES CO and THINGS H i surveys. Focusing on regions with bright CO emission, we find a CO dispersion value {σ }{{CO}} = 7.3 ± 1.7 km s‑1. The corresponding H i dispersion {σ }{{H}{{I}}} = 11.7 ± 2.3 km s‑1, yielding a mean dispersion ratio {σ }{{H}{{I}}}/{σ }{{CO}} = 1.4 ± 0.2, independent of radius. We find that the CO velocity dispersion increases toward lower peak fluxes. This is consistent with previous work where we showed that when using spectra averaged (“stacked”) over large areas, larger values for the CO dispersion are found, and a lower ratio {σ }{{H}{{I}}}/{σ }{{CO}} = 1.0 ± 0.2. The stacking method is more sensitive to low-level diffuse emission, whereas individual profiles trace narrow-line, GMC-dominated, bright emission. These results provide further evidence that disk galaxies contain not only a thin, low velocity dispersion, high density
Free Keywords:galaxies: ISM; galaxies: star formation; ISM: molecules; radio lines: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6256
URL:http://cdsads.u-strasbg.fr/abs/2016AJ....151...15M
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