Mapping the Spatial Distribution of Dust Extinction within NGC 0959
Abstract
Combining broadband optical and mid-IR images with a pixel-to-pixel analysis, we measure the detailed distribution of dust extinction within nearby late-type galaxy NGC 0959. We present a method using the observed ground-based V to Spitzer 3.6 micron flux ratio and the theoretical ratio calculated from an SED library to estimate the amount of dust extinction in each pixel. Commonly used methods (e.g., with far-IR or with narrow band filters) have lower spatial resolution, are inferred from radial surface brightness profiles (azimuthally averaged in annuli), or are restricted to lines-of-sight toward star-formation regions. Our method, on the other hand, is able to map the detailed two-dimensional distribution of dust extinction, and is applicable to both young and old stellar populations. Another important difference is that---while other methods require specific filters to measure dust extinction---our method requires only two commonly available optical broadband filters and the mid-IR 3.6 micron (L-band) filter. Even though the dust-lanes are not clearly visible in the lower resolution images used in this analysis, our result clearly traces the detailed distribution of dust---silhouetted against galaxy's disk---in the high-resolution images from the Hubble Space Telescope. Our method, therefore, is a powerful tool that could be used to measure the detailed distribution of dust extinction within higher redshift galaxies observed both with HST (optical) and JWST (mid-IR), and to distinguish properties of dust within bulges, bars, spiral arms and/or inter-arm regions. Also, once enough galaxies are studied to establish general trends of dust extinction based on galaxy type and structure, we plan to apply our method to predict the observed luminosity at a range of wavelengths for galaxies modeled ab initio.
Funding for this project is provided through NASA/ADP grant NNX07AH50G and JWST grant NAG5-12460.- Publication:
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American Astronomical Society Meeting Abstracts #213
- Pub Date:
- January 2009
- Bibcode:
- 2009AAS...21341209T