The GALEX/S4G Surface Brightness and Color Profiles Catalog - I. Surface
  Photometry and Color Gradients of Galaxies
  We present new, spatially resolved, surface photometry in FUV and NUV from
images obtained by the $\textit{Galaxy Evolution Explorer}$ (GALEX), and IRAC1
(3.6 $\mu$m) photometry from the $\textit{Spitzer Survey of Stellar Structure
in Galaxies}$ (S$^{4}$G) (Sheth et al. 2010). 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 (2000). 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 to 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 $3\times 10^{8}$ $M_{\odot}$
kpc$^{-2}$ in stellar mass surface density, the average specific star formation
rate for star forming and quiescent galaxies remains relatively flat with
radius. However, a large fraction of GALEX Green Valley galaxies (defined in
Bouquin et al. 2015) shows a radial decrease in specific star formation rate.
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 towards the red sequence of
quiescent galaxies.
