Untangling the nature of spatial variations of cold dust properties in star forming galaxies
- Department of Astronomy, University of Massachusetts, Amherst, MA 01002 (United States)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)
- European Southern Observatory, Karl-Schwarzchild-Str. 2, D-85748 Garching-bei-München (Germany)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- Max-Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany)
- INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States)
- MMT Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721 (United States)
We investigate the far-infrared (IR) dust emission for 20 local star forming galaxies from the Key Insights on Nearby Galaxies: A Far-IR Survey with Herschel (KINGFISH) sample. We model the far-IR/submillimeter spectral energy distribution (SED) using images from Spitzer Space Telescope and Herschel Space Observatory. We calculate the cold dust temperature (T{sub c} ) and emissivity (β) on a pixel by pixel basis (where each pixel ranges from 0.1 to 3 kpc{sup 2}) using a two-temperature modified blackbody fitting routine. Our fitting method allows us to investigate the resolved nature of temperature and emissivity variations by modeling from the galaxy centers to the outskirts (physical scales of ∼15-50 kpc, depending on the size of the galaxy). We fit each SED in two ways: (1) fit T{sub c} and β simultaneously, (2) hold β constant and fit T{sub c} . We compare T{sub c} and β with star formation rates (calculated from L{sub Hα} and L{sub 24μm}), the luminosity of the old stellar population (traced through L{sub 3.6μm}), and the dust mass surface density (traced by 500 μm luminosity, L{sub 500}). We find a significant trend between SFR/L{sub 500} and T{sub c} , implying that the flux of hard UV photons relative to the amount of dust is significantly contributing to the heating of the cold, or diffuse, dust component. We also see a trend between L{sub 3.6}/L{sub 500} and β, indicating that the old stellar population contributes to the heating at far-IR/submillimeter wavelengths. Finally, we find that when β is held constant, T{sub c} exhibits a strongly decreasing radial trend, illustrating that the shape of the far-IR SED is changing radially through a galaxy, thus confirming on a sample almost double in size the trends observed in Galametz et al.
- OSTI ID:
- 22365666
- Journal Information:
- Astrophysical Journal, Vol. 789, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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