Publication: The GALEX/S(4)G Surface Brightness and Color Profiles Catalog. I. Surface Photometry and Color Gradients of Galaxies
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2018-02
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University Chicago Press
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Abstract
We present new spatially resolved surface photometry in the far-ultraviolet (FUV) and near-ultraviolet (NUV) from images obtained by the Galaxy Evolution Explorer (GALEX) and IRAC1 (3.6 mu m) photometry from the Spitzer Survey of Stellar Structure in Galaxies (S(4)G). We analyze the radial surface brightness profiles mu(FUV), mu(NUV), and mu[3.6], as well as the radial profiles of (FUV - NUV), (NUV -[3.6]), and (FUV -[3.6]) colors in 1931 nearby galaxies (z < 0.01). The analysis of the 3.6 mu m surface brightness profiles also allows us to separate the bulge and disk components in a quasi-automatic way and to compare their light and color distribution with those predicted by the chemo-spectrophotometric models for the evolution of galaxy disks of Boissier & Prantzos. The exponential disk component is best isolated by setting an inner radial cutoff and an upper surface brightness limit in stellar mass surface density. The best-fitting models to the measured scale length and central surface brightness values yield distributions of spin and circular velocity within a factor of two of those obtained via direct kinematic measurements. We find that at a surface brightness fainter than mu([3.6]) = 20.89 mag arcsec(-2), or below 3 x 10(8) M-circle dot kpc(-2) in stellar mass surface density, the average specific star formation rate (sSFR) for star-forming and quiescent galaxies remains relatively flat with radius. However, a large fraction of GALEX Green Valley galaxies show a radial decrease in sSFR. This behavior suggests that an outside-in damping mechanism, possibly related to environmental effects, could be testimony of an early evolution of galaxies from the blue sequence of star-forming galaxies toward the red sequence of quiescent galaxies.
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© 2018. The American Astronomical Society. All rights reserved. We acknowledge financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/under REA grant agreement number PITN-GA-2011-289313. AYKB also thanks Professor Emeritus John E. Beckman for the valuable suggestions during private communications. JHK thanks the Astrophysical Research Institute of Liverpool John Moores University for their hospitality and the Spanish Ministry of Education, Culture and Sports for financial support of his visit there through grant number PR2015-00512. JHK acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under grant numbers AYA2013-41243-P and AYA2016-76219-P. We acknowledge GALEXview and the STScI team for the data provided. We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr). This research made use of Astropy, a community-developed core Python package for astronomy (Astropy Collaboration et al. 2013). We are grateful to our anonymous referee for the very constructive and excellent suggestions.