Dissecting Nearby Galaxies with piXedfit: I. Spatially Resolved
  Properties of Stars, Dust, and Gas as Revealed by Panchromatic SED Fitting
  We study spatially resolved properties (on spatial scales of $\sim 1-2$ kpc
out to at least $3$ effective radii) of the stars, dust, and gas in ten nearby
spiral galaxies. The properties of the stellar population and dust are derived
by fitting the spatially resolved spectral energy distribution (SED) with more
than 20 photometric bands ranging from far-ultraviolet to far-infrared. Our
newly developed software piXedfit performs point spread function matching of
images, pixel binning, and models the stellar light, dust attenuation, dust
emission, and emission from a dusty torus heated by an active galactic nucleus
simultaneously through the energy balance approach. With this self-consistent
analysis, we present the spatially resolved version of the IRX--$\beta$
relation, finding that it is consistent with the relationship from the
integrated photometry. We show that the old stellar populations contribute to
the dust heating, which causes an overestimation of star formation rate (SFR)
derived from the total ultraviolet and infrared luminosities on kpc scales.
With archival high-resolution maps of atomic and molecular gas, we study the
radial variation of the properties of the stellar populations (including
stellar mass, age, metallicity, and SFR), dust (including dust mass, dust
temperature, and abundance of polycyclic aromatic hydrocarbon), gas, as well as
dust-to-stellar mass and dust-to-gas mass ratios. We observe a depletion of
molecular gas mass fraction in the central region of the majority of the
galaxies, suggesting that the lack of available fuel is an important factor in
suppressing the specific SFR at the center.
