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Comparing [C II] , HI, and CO Dynamics of Nearby Galaxies

de Blok, W. J. G. and Walter, F. and Smith, J.-D. T. and Herrera-Camus, R. and Bolatto, A. D. and Requena-Torres, M. A. and Crocker, A. F. and Croxall, K. V. and Kennicutt, R. C. and Koda, J. and Armus, L. and Boquien, M. and Dale, D. and Kreckel, K. and Meidt, S. (2016) Comparing [C II] , HI, and CO Dynamics of Nearby Galaxies. Astronomical Journal, 152 (2). Art. No. 51. ISSN 0004-6256. doi:10.3847/0004-6256/152/2/51.

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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 Iand 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 Idistribution. 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Walter, F.0000-0003-4793-7880
Smith, J.-D. T.0000-0003-1545-5078
Herrera-Camus, R.0000-0002-2775-0595
Bolatto, A. D.0000-0002-5480-5686
Crocker, A. F.0000-0001-8513-4945
Croxall, K. V.0000-0002-5258-7224
Kennicutt, R. C.0000-0001-5448-1821
Koda, J.0000-0002-8762-7863
Armus, L.0000-0003-3498-2973
Boquien, M.0000-0003-0946-6176
Dale, D.0000-0002-5782-9093
Kreckel, K.0000-0001-6551-3091
Meidt, S.0000-0002-6118-4048
Additional Information:© 2016 The American Astronomical Society. Received 2015 December 3; accepted 2016 April 28; published 2016 August 4. W.J.G.d.B. was supported by the European Commission (grant FP7-PEOPLE-2012-CIG #333939). Beyond the Peak research has been supported by a NASA/JPL grant (RSA 1427378). J.D.S. gratefully acknowledges visiting support from the Alexander von Humboldt Foundation and the Max Planck Institute für Astronomie. A.D.B. and R.H.C. acknowledge support from grants USRA-SOF020098, NSF-AST0955836, and NSF-AST1412419, as well as visiting support from the Humboldt Foundation. This work is based in part on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). Financial support for this work was provided by NASA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Marie Curie FellowshipFP7-PEOPLE-2012-CIG 333939
Alexander von Humboldt FoundationUNSPECIFIED
Max Planck Institute für AstronomieUNSPECIFIED
Universities Space Research Association (USRA)SOF020098
Subject Keywords:galaxies: fundamental parameters – galaxies: ISM – galaxies: kinematics and dynamics – radio lines: galaxies – submillimeter: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20160810-133835678
Persistent URL:
Official Citation:W. J. G. de Blok et al 2016 The Astronomical Journal 152 51
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69544
Deposited By: Tony Diaz
Deposited On:10 Aug 2016 21:30
Last Modified:11 Nov 2021 04:16

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