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Dust in the Diffuse Emission of the Galactic Plane: The Herschel/Spitzer Spectral Energy Distribution Fitting

Compiègne, M. and Flagey, N. and Noriega-Crespo, A. and Martin, P. G. and Bernard, J.-P. and Paladini, R. and Molinari, S. (2010) Dust in the Diffuse Emission of the Galactic Plane: The Herschel/Spitzer Spectral Energy Distribution Fitting. Astrophysical Journal Letters, 724 (1). L44-L47. ISSN 2041-8205. http://resolver.caltech.edu/CaltechAUTHORS:20101210-113430005

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Abstract

The first Herschel Hi-Gal images of the Galactic plane unveil the far-infrared diffuse emission of the interstellar medium with an unprecedented angular resolution and sensitivity. In this Letter, we present the first analysis of these data in combination with those of Spitzer GLIMPSE and MIPSGAL. We selected a relatively diffuse and low excitation region of the l ~ 59° Hi-Gal Science Demonstration Phase field to perform a pixel-by-pixel fitting of the 8 to 500 μm spectral energy distribution (SED) using the DustEM dust emission model. We derived maps of the very small grain (VSG) and polycyclic aromatic hydrocarbon (PAH) abundances from the model. Our analysis allows us to illustrate that the aromatic infrared band intensity does not necessarily trace the PAH abundance but rather the product of "abundance × column density × intensity of the exciting radiation field." We show that the spatial structure of PACS 70 μm maps resemble the shorter wavelengths (e.g., IRAC 8 μm) maps, because they trace both the intensity of exciting radiation field and column density. We also show that the modeled VSG contribution to PACS 70 μm (PACS 160 μm) band intensity can be up to 50% (7%). The interpretation of diffuse emission spectra at these wavelengths must take stochastically heated particles into account. Finally, this preliminary study emphasizes the potential of analyzing the full dust SED sampled by Herschel and Spitzer data, with a physical dust model (DustEM) to reach the properties of the dust at simultaneously large and small scales.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/2041-8205/724/1/L44DOIUNSPECIFIED
http://iopscience.iop.org/2041-8205/724/1/L44PublisherUNSPECIFIED
Additional Information:© 2010 American Astronomical Society. Received 2010 July 26; accepted 2010 October 8; published 2010 October 28. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. The Spitzer Space Telescope is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.
Classification Code:PACS: 98.58.Ca; 98.58.Bz; 98.58.Jg; 95.30.Ky
Record Number:CaltechAUTHORS:20101210-113430005
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20101210-113430005
Official Citation:M. Compiègne et al 2010 ApJ 724 L44 doi: 10.1088/2041-8205/724/1/L44
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21298
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:10 Dec 2010 21:03
Last Modified:29 Aug 2014 14:46

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