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Radial distribution of stars, gas, and dust in sings galaxies. II. Derived dust properties

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Muñoz Mateos, J. C. and Gil de Paz, Armando and Boissier, S. and Zamorano Calvo, Jaime and Dale, D. A. and Pérez González, Pablo Guillermo and Gallego Maestro, Jesús and Madore, B. F. and Bendo, G. and Thornley, M. D. and Draine, B. T. and Boselli, A. and Buat, V. and Calzetti, D. and Moustakas, J. and Kennicutt, R. C. Jr. (2009) Radial distribution of stars, gas, and dust in sings galaxies. II. Derived dust properties. Astrophysical journal, 701 (2). pp. 1965-1991. ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/701/2/1965


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Abstract

We present a detailed analysis of the radial distribution of dust properties in the SINGS sample, performed on a set of ultraviolet (UV), infrared (IR), and Hi surface brightness profiles, combined with published molecular gas profiles and metallicity gradients. The internal extinction, derived from the total-IR (TIR)-to-far-UV (FUV) luminosity ratio, decreases with radius, and is larger in Sb-Sbc galaxies. The TIR-to-FUV ratio correlates with the UV spectral slope β, following a sequence shifted to redder UV colors with respect to that of starbursts. The star formation history (SFH) is identified as the main driver of this departure. Both L_TIR)/L_FUV and β correlate well with metallicity, especially in moderately face-on galaxies. The relation shifts to redder colors with increased scatter in more edge-on objects. By applying physical dust models to our radial spectral energy distributions, we have derived radial profiles of the total dust mass surface density, the fraction of the total dust mass contributed by polycyclic aromatic hydrocarbons (PAHs), and the intensity of the radiation field heating the grains. The dust profiles are exponential, their radial scale length being constant from Sb to Sd galaxies (only ~ 10% larger than the stellar scale length). Many S0/a-Sab galaxies have central depressions in their dust radial distributions. The PAH abundance increases with metallicity for 12 + log(O/H) < 9, and at larger metallicities the trend flattens and even reverses, with the SFH being a plausible underlying driver for this behavior. The dust-to-gas ratio is also well correlated with metallicity and therefore decreases with galactocentric radius. Although most of the total emitted IR power (especially in the outer regions of disks) is contributed by dust grains heated by diffuse starlight with a similar intensity as the local Milky Way radiation field, a small amount of the dust mass (~ 1%) is required to be exposed to very intense starlight in order to reproduce the observed fluxes at 24 μ m, accounting for ~ 10% of the total integrated IR power.


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© 2009. The American Astronomical Society. J.C.M.M. acknowledges the receipt of a Formacion del Profesorado Universitario fellowship from the Spanish Ministerio de Educación y Ciencia. J.C.M.M., A.G.d.P., J.Z., P.G.P., and J.G. are partially financed by the Spanish Programa Nacional de Astronomía y Astrofísica under grant AYA2006-02358. A.G.d.P. is also financed by the MAGPOP EU Marie Curie Research Training Network. We thank the anonymous referee for valuable comments that have improved the paper. We have made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology (Caltech) under contract with NASA. GALEX is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology. This work is part of SINGS, the Spitzer Infrared Nearby Galaxies Survey. The Spitzer Space Telescope is operated by the Jet Propulsion Laboratory, Caltech, under NASA contract 1403. This work also makes use of data from THINGS, The H i Nearby Galaxies Survey. We thank A. Leroy and F. Walter for kindly providing the H i radial profiles. We also thank L. Cortese for providing his fit for Figure 5.

Uncontrolled Keywords:Spectral energy-distribution; Compact dwarf galaxies; Multiband imaging photometer; Spitzer-space-telescope; Aromatic-hydrocarbon emission; Disk-dominated galaxies; Nearby spiral galaxies; Infrared array camera; 160 μm; Forming galaxies
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:34151
Deposited On:05 Nov 2015 13:55
Last Modified:10 Dec 2018 15:05

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