Star formation and dust extinction properties of local galaxies from the AKARI-GALEX all-sky surveys: First results from the most secure multiband sample from the far-ultraviolet to the far-infrared
Publication date: 22 January 2010
Authors: Takeuchi, T.T. et al.
Journal: Astronomy & Astrophysics preprint
Aims. We explore spectral energy distributions (SEDs), star formation (SF), and dust extinction properties of galaxies in the Local Universe.
Methods. The AKARI All-Sky Survey provided the first bright point source catalog detected at 90 micron. Beginning with this catalog, we selected galaxies by matching the AKARI sources with those in the IRAS Point Source Catalog Redshift Survey. We measured the total GALEX FUV and NUV flux densities with a photometry software we specifically developed for this purpose. In a further step we matched this sample with the Sloan Digital Sky Survey (SDSS) and Two Micron All Sky Survey (2MASS) galaxies. With this procedure we obtained a basic sample which consists of 776 galaxies. After removing objects whose photometry was contaminated by foreground sources (mainly in the SDSS), we defined the "secure sample" which contains 607 galaxies.
Results. The sample galaxies have redshifts of <~ 0.15, and their 90-micron luminosities range from 106 to 1012 Lsun, with a peak at 1010 Lsun. The SEDs display a large variety, especially more than four orders of magnitude at the mid-far-infrared (M-FIR), but if we sort the sample with respect to 90 micron, the average SED shows a coherent trend: the more luminous an SED at 90 micron, the redder the global SED becomes. The Mr-NUV - r color-magnitude relation of our sample does not show bimodality, and the distribution is centered on the green valley.
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