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The JCMT Nearby Galaxies Legacy Survey - IV. Velocity dispersions in the molecular interstellar medium in spiral galaxies
Wilson, C. D.1; Warren, B. E.1; Irwin, J.2; Knapen, J. H.3,4; Israel, F. P.5; Serjeant, S.6; Attewell, D.1; Bendo, G. J.7; Brinks, E.8; Butner, H. M.9; Clements, D. L.7; Leech, J.10; Matthews, H. E.11; Muhle, S.12; Mortier, A. M. J.13; Parkin, T. J.1; Petitpas, G.14; Tan, B. K.10; Tilanus, R. P. J.15,16; Usero, A.17; Vaccari, M.18; van der Werf, P.5; Wiegert, T.19; Zhu, M.20
AbstractAn analysis of large-area CO J = 3-2 maps from the James Clerk Maxwell Telescope for 12 nearby spiral galaxies reveals low velocity dispersions in the molecular component of the interstellar medium. The three lowest luminosity galaxies show a relatively flat velocity dispersion as a function of radius while the remaining nine galaxies show a central peak with a radial fall-off within 0.2-0.4r(25). Correcting for the average contribution due to the internal velocity dispersions of a population of giant molecular clouds, the average cloud-cloud velocity dispersion across the galactic discs is 6.1 +/- 1.0 km s-1 (standard deviation of 2.9 km s-1), in reasonable agreement with previous measurements for the Galaxy and M33. The cloud-cloud velocity dispersion derived from the CO data is on average two times smaller than the H i velocity dispersion measured in the same galaxies. The low cloud-cloud velocity dispersion implies that the molecular gas is the critical component determining the stability of the galactic disc against gravitational collapse, especially in those regions of the disc which are H-2 dominated. The cloud-cloud velocity dispersion shows a significant positive correlation with both the far-infrared luminosity, which traces the star formation activity, and the K-band absolute magnitude, which traces the total stellar mass. For three galaxies in the Virgo cluster, smoothing the data to a resolution of 4.5 kpc (to match the typical resolution of high-redshift CO observations) increases the measured velocity dispersion by roughly a factor of 2, comparable to the dispersion measured recently in a normal galaxy at z = 1. This comparison suggests that the mass and star formation rate surface densities may be similar in galaxies from z = 0 to 1 and that the high star formation rates seen at z = 1 may be partly due to the presence of physically larger molecular gas discs.
KeywordStars: Formation Ism: Molecules Galaxies: Ism Galaxies: Kinematics And Dynamics Galaxies: Spiral
Indexed BySCI
WOS IDWOS:000286004300002
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Cited Times:30[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Affiliation1.McMaster Univ, Dept Phys & Astron, Hamilton, ON L8S 4M1, Canada
2.Queens Univ, Dept Phys Engn Phys & Astron, Kingston, ON K7L 3N6, Canada
3.Inst Astrofis Canarias, E-38200 San Cristobal la Laguna, Tenerife, Spain
4.Univ La Laguna, Dept Astrofis, E-38205 Tenerife, Spain
5.Leiden Univ, Sterrewacht Leiden, NL-2300 RA Leiden, Netherlands
6.Open Univ, Dept Phys & Astron, Milton Keynes MK7 6AA, Bucks, England
7.Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Astrophys Grp, London SW7 2AZ, England
8.Univ Hertfordshire, Ctr Astrophys Res, Hatfield AL10 9AB, Herts, England
9.James Madison Univ, Dept Phys & Astron, Harrisonburg, VA 22807 USA
10.Univ Oxford, Dept Phys, Oxford OX1 3RH, England
11.Natl Res Council Canada, Herzberg Inst Astrophys, DRAO, Penticton, BC V2A 69J, Canada
12.Joint Inst VLBI Europe, NL-7990 AA Dwingeloo, Netherlands
13.Univ Edinburgh, Scottish Univ Phys Alliance, Inst Astron, Royal Observ, Edinburgh EH9 3HJ, Midlothian, Scotland
14.Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
15.Joint Astron Ctr, Hilo, HI 96720 USA
16.Netherlands Org Sci Res, NL-2509 AC The Hague, Netherlands
17.OAN, Observ Madrid, E-28014 Madrid, Spain
18.Univ Padua, Dipartimento Astron, I-35122 Padua, Italy
19.Univ Manitoba, Dept Phys & Astron, Winnipeg, MB R3T 2N2, Canada
20.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China
Recommended Citation
GB/T 7714
Wilson, C. D.,Warren, B. E.,Irwin, J.,et al. The JCMT Nearby Galaxies Legacy Survey - IV. Velocity dispersions in the molecular interstellar medium in spiral galaxies[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2011,410(3):1409-1422.
APA Wilson, C. D..,Warren, B. E..,Irwin, J..,Knapen, J. H..,Israel, F. P..,...&Zhu, M..(2011).The JCMT Nearby Galaxies Legacy Survey - IV. Velocity dispersions in the molecular interstellar medium in spiral galaxies.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,410(3),1409-1422.
MLA Wilson, C. D.,et al."The JCMT Nearby Galaxies Legacy Survey - IV. Velocity dispersions in the molecular interstellar medium in spiral galaxies".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 410.3(2011):1409-1422.
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