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Title: A comparative study of giant molecular clouds in M51, M33, and the Large Magellanic Cloud

We compare the properties of giant molecular clouds (GMCs) in M51 identified by the Plateau de Bure Interferometer Whirlpool Arcsecond Survey with GMCs identified in wide-field, high-resolution surveys of CO emission in M33 and the Large Magellanic Cloud (LMC). We find that GMCs in M51 are larger, brighter, and have higher velocity dispersions relative to their sizes than equivalent structures in M33 and the LMC. These differences imply that there are genuine variations in the average mass surface density 〈Σ{sub H{sub 2}}〉 of the different GMC populations. To explain this, we propose that the pressure in the interstellar medium surrounding the GMCs plays a role in regulating their density and velocity dispersion. We find no evidence for a correlation between size and linewidth in M51, M33, or the LMC when the CO emission is decomposed into GMCs, although moderately robust correlations are apparent when regions of contiguous CO emission (with no size limitation) are used. Our work demonstrates that observational bias remains an important obstacle to the identification and study of extragalactic GMC populations using CO emission, especially in molecule-rich galactic environments.
Authors:
; ; ;  [1] ; ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  2. Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, F-38406 Saint Martin d'Hères (France)
  3. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
  4. School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)
  5. Observatorio Astronómico Nacional, Observatorio de Madrid, Alfonso XII, 3, E-28014 Madrid (Spain)
  6. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  7. Instituto Radioastronomía Milimétrica, Avenida Divina Pastora 7, Nucleo Central, E-18012 Granada (Spain)
Publication Date:
OSTI Identifier:
22348516
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; CORRELATIONS; DENSITY; DISPERSIONS; EMISSION; GALAXIES; INTERFEROMETERS; MAGELLANIC CLOUDS; MASS; MOLECULES; RESOLUTION; SURFACES; VARIATIONS