Letter to the Editor

HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE): The Large Magellanic Cloud dust^*

¹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA e-mail: meixner@stsci.edu
² Visiting Scientist at Smithsonian Astrophysical Observatory, Harvard-CfA, 60 Garden St., Cambridge, MA, 02138, USA
³ CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, 91191 Gif-sur-Yvette, France
⁴ Center for Astrophysics, 60 Garden St., MS 67, Harvard University, Cambridge, MA 02138, USA
⁵ Fellow
⁶ Steward Observatory, University of Arizona, 933 North Cherry Ave., Tucson, AZ 85721, USA
⁷ Centre d' Étude Spatiale des Rayonnements, CNRS, 9 Av. du Colonel Roche, BP 4346, 31028 Toulouse, France
⁸ Department of Astronomy, Lab for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742-2421, USA
⁹ Observatoire Astronomique de Strasbourg, 11 rue de l'universite, 67000 Strasbourg, France
¹⁰ Department of Astronomy, 475 North Charter St., University of Wisconsin, Madison, WI 53706, USA
¹¹ Johns Hopkins University, Department of Physics and Astronomy, Homewood Campus, Baltimore, MD 21218, USA
¹² Louisiana State University, Department of Physics & Astronomy, 233-A Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001, USA
¹³ Department of Astronomy, University of Virginia, and National Radio Astronomy Observatory, PO Box 3818, Charlottesville, VA 22903, USA
¹⁴ Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
¹⁵ Centre for Supercomputing and Astrophysics, Swinburne University of Technology, Hawthorn VIC 3122, Australia
¹⁶ Sterrewacht Leiden, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
¹⁷ Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics & Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
¹⁸ Astronomy & Space Science, Sejong University, 143-747, Seoul, South Korea
¹⁹ 314 Physics Building, Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
²⁰ Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
²¹ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
²² MSSL, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
²³ School of Physical & Geographical Sciences, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK
²⁴ Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, Sakai, Osaka 599-8531, Japan
²⁵ Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125, USA
²⁶ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 85748 Garching, Germany
²⁷ Stratospheric Observatory for Infrared Astronomy, Universities Space Research Association, Mail Stop 211-3, Moffett Field, CA 94035, USA
²⁸ Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile
²⁹ Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA, 91101, USA
³⁰ Astrophysique de Paris, Institute (IAP), CNRS UPR 341, 98bis boulevard Arago, 75014 Paris, France
³¹ Space Science Institute, 4750 Walnut St. Suite 205, Boulder, CO 80301, USA

Received: 31 March 2010
Accepted: 14 April 2010

Abstract

The HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) of the Magellanic Clouds will use dust emission to investigate the life cycle of matter in both the Large and Small Magellanic Clouds (LMC and SMC). Using the Herschel Space Observatory's PACS and SPIRE photometry cameras, we imaged a 2° × 8° strip through the LMC, at a position angle of ~22.5° as part of the science demonstration phase of the Herschel mission. We present the data in all 5 Herschel bands: PACS 100 and 160 μm and SPIRE 250, 350 and 500 μm. We present two dust models that both adequately fit the spectral energy distribution for the entire strip and both reveal that the SPIRE 500 μm emission is in excess of the models by ~6 to 17%. The SPIRE emission follows the distribution of the dust mass, which is derived from the model. The PAH-to-dust mass (f_PAH) image of the strip reveals a possible enhancement in the LMC bar in agreement with previous work. We compare the gas mass distribution derived from the HI 21 cm and CO J = 1–0 line emission maps to the dust mass map from the models and derive gas-to-dust mass ratios (GDRs). The dust model, which uses the standard graphite and silicate optical properties for Galactic dust, has a very low GDR = 65_-18⁺¹⁵ making it an unrealistic dust model for the LMC. Our second dust model, which uses amorphous carbon instead of graphite, has a flatter emissivity index in the submillimeter and results in a GDR = 287_-42⁺²⁵ that is more consistent with a GDR inferred from extinction.