Multi-dimensional analysis of the chemical and physical properties of
  spiral galaxies
  In this thesis, wide-field 2D spectroscopy is employed in order to
characterise the nebular properties of late-type field galaxies. The
observations performed for this dissertation represent the first endeavour to
obtain full 2D coverage of the disks of a sample of nearby spiral galaxies, by
the application of the Integral Field Spectroscopy (IFS) technique, under the
PPAK IFS Nearby Galaxies Survey: PINGS. A self-consistent methodology is
defined in terms of observation, data reduction and analysis techniques for
this and upcoming IFS surveys, as well as providing a whole new set of IFS
visualization and analysis software made available for the public domain
(PINGSoft). The scientific analysis comprises the study of the integrated
properties of the ionized gas and a detailed 2D study from the emission line
spectra of four selected galaxies. Evidence is found suggesting that
measurements of emission lines of classical HII regions are not only aperture,
but spatial dependent, and therefore, the derived physical parameters and
metallicity content may significantly depend on the morphology of the region,
on the extraction aperture and on the signal-to-noise of the observed spectrum.
Furthermore, observational evidence of non-linear multi-modal abundance
gradients in normal spiral galaxies is found, consistent with a flattening in
the innermost and outermost parts of the galactic discs, with important
implications in terms of the chemical evolution of galaxies.
