Resolving galaxies in time and space: I: Applying STARLIGHT to CALIFA
  data cubes
  Fossil record methods based on spectral synthesis techniques have matured
over the past decade, and their application to integrated galaxy spectra
fostered substantial advances on the understanding of galaxies and their
evolution. Yet, because of the lack of spatial resolution, these studies are
limited to a global view, providing no information about the internal physics
of galaxies. Motivated by the CALIFA survey, which is gathering Integral Field
Spectroscopy over the full optical extent of 600 galaxies, we have developed an
end-to-end pipeline which: (i) partitions the observed data cube into Voronoi
zones in order to, when necessary and taking due account of correlated errors,
increase the S/N, (ii) extracts spectra, including propagated errors and
bad-pixel flags, (iii) feeds the spectra into the STARLIGHT spectral synthesis
code, (iv) packs the results for all galaxy zones into a single file, (v)
performs a series of post-processing operations, including zone-to-pixel image
reconstruction and unpacking the spectral and stellar population properties
into multi-dimensional time, metallicity, and spatial coordinates. This paper
provides an illustrated description of this whole pipeline and its products.
Using data for the nearby spiral NGC 2916 as a show case, we go through each of
the steps involved, presenting ways of visualizing and analyzing this manifold.
These include 2D maps of properties such as the v-field, stellar extinction,
mean ages and metallicities, mass surface densities, star formation rates on
different time scales and normalized in different ways, 1D averages in the
temporal and spatial dimensions, projections of the stellar light and mass
growth (x,y,t) cubes onto radius-age diagrams, etc. The results illustrate the
richness of the combination of IFS data with spectral synthesis, providing a
glimpse of what is to come from CALIFA and future surveys. (Abridged)
