Title

Dust and gas in the magellanic clouds from the heritage Herschel Key Project. I. Dust properties and insights into the origin of the submillimeter excess emission

Authors

Karl D. Gordon, Space Telescope Science Institute
Julia Roman-Duval, Space Telescope Science Institute
B. O.T. Caroline, Université de Strasbourg
Margaret Meixner, Space Telescope Science Institute
Brian Babler, University of Wisconsin-Madison
Jean Philippe Bernard, Universite Paul Sabatier Toulouse III
Alberto Bolatto, University of Maryland, College Park
Martha L. Boyer, NASA Goddard Space Flight Center
Geoffrey C. Clayton, Louisiana State University
Charles Engelbracht, The University of Arizona
Yasuo Fukui, Nagoya University
Maud Galametz, European Southern Observatory
Frederic Galliano, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Sacha Hony, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Annie Hughes, Max Planck Institute for Astronomy
Remy Indebetouw, University of Virginia
Frank P. Israel, Leiden Observatory Research Institute
Katherine Jameson, University of Maryland, College Park
Akiko Kawamura, National Institutes of Natural Sciences - National Astronomical Observatory of Japan
Vianney Lebouteiller, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Aigen Li, University of Missouri
Suzanne C. Madden, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Mikako Matsuura, University College London
Karl Misselt, The University of Arizona
Edward Montiel, Louisiana State University
K. Okumura, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Toshikazu Onishi, Osaka Prefecture University
Pasquale Panuzzo, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Deborah Paradis, Universite Paul Sabatier Toulouse III
Monica Rubio, Universidad de Chile
Karin Sandstrom, The University of Arizona
Marc Sauvage, Astrophysique, Instrumentation et Modélisation de Paris-Saclay
Jonathan Seale, Space Telescope Science Institute

Document Type

Article

Publication Date

12-20-2014

Abstract

The dust properties in the Large and Small Magellanic clouds (LMC/SMC) are studied using the HERITAGE Herschel Key Project photometric data in five bands from 100 to 500 μm. Three simple models of dust emission were fit to the observations: a single temperature blackbody modified by a power-law emissivity (SMBB), a single temperature blackbody modified by a broken power-law emissivity (BEMBB), and two blackbodies with different temperatures, both modified by the same power-law emissivity (TTMBB). Using these models, we investigate the origin of the submillimeter excess, defined as the submillimeter emission above that expected from SMBB models fit to observations <200 μm. We find that the BEMBB model produces the lowest fit residuals with pixel-averaged 500 μm submillimeter excesses of 27% and 43% for the LMC and SMC, respectively. Adopting gas masses from previous works, the gas-to-dust ratios calculated from our fitting results show that the TTMBB fits require significantly more dust than are available even if all the metals present in the interstellarmedium (ISM) were condensed into dust. This indicates that the submillimeter excess ismore likely to be due to emissivity variations than a second population of colder dust. We derive integrated dust masses of (7.3 ± 1.7) × 105 and (8.3 ± 2.1) × 104 M⊙ for the LMC and SMC, respectively. We find significant correlations between the submillimeter excess and other dust properties; further work is needed to determine the relative contributions of fitting noise and ISM physics to the correlations.

Publication Source (Journal or Book title)

Astrophysical Journal

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