Structure and Colors of Diffuse Emission in the Spitzer Galactic First Look Survey
Abstract
We investigate the density structure of the interstellar medium using new high-resolution maps of the 8 micron, 24 micron, and 70 micron surface brightness towards a molecular cloud in the Gum Nebula, made as part of the Spitzer Space Telescope Galactic First Look Survey. The maps are correlated with 100 micron images measured with IRAS. At 24 and 70 micron, the spatial power spectrum of surface brightness follows a power law with spectral index -3.5. At 24 micron, the power law behavior is remarkably consistent from the 0.2 degree size of our maps down to the 5 arcsecond spatial resolution. Thus, the structure of the 24 micron emission is self-similar even at milliparsec scales. The combined power spectrum produced from Spitzer 24 micron and IRAS 25 micron images is consistent with a change in the power law exponent from -2.6 to -3.5. The decrease may be due to the transition from a two-dimensional to three-dimensional structure. Under this hypothesis, we estimate the thickness of the emitting medium to be 0.3 pc.
Cite
@article{arxiv.astro-ph/0406237,
title = {Structure and Colors of Diffuse Emission in the Spitzer Galactic First Look Survey},
author = {James G. Ingalls and M. -A. Miville-Deschênes and William T. Reach and A. Noriega-Crespo and Sean J. Carey and F. Boulanger and S. R. Stolovy and Deborah L. Padgett and M. J. Burgdorf and S. B. Fajardo-Acosta and W. J. Glaccum and G. Helou and D. W. Hoard and J. Karr and J. O'Linger and L. M. Rebull and J. Rho and J. R. Stauffer and S. Wachter},
journal= {arXiv preprint arXiv:astro-ph/0406237},
year = {2009}
}
Comments
13 Pages, 3 Figures, to be published in Astrophysical Journal Supplement Series (Spitzer Special Issue), volume 154. Uses aastex v5.2