Multi-dimensional analysis of the chemical and physical properties of spiral galaxies
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Abstract
The PPAK Integral Field Spectroscopy (IFS) Nearby Galaxies Survey: PINGS, a 2-dimensional spectroscopic mosaicking of 17 nearby disk galaxies in the optical wavelength range. This project represents the first attempt to obtain continuous coverage spectra of the whole surface of a galaxy in the nearby universe. The final data set comprises more than 50000 individual spectra, covering in total an observed area of nearly 80 arcmin square. The powerful capabilities of wide-field 2D spectroscopic studies are proven. The chemical composition of the whole surface of a spiral galaxy is characterised for the first time as a function not only of radius, but of the intrinsic morphology of the galaxy, allowing a more realistic determination of their physical properties. The methodology, analysis and results of this dissertation will hopefully contribute in a significant way to understand the nature of the physical and chemical properties of the gas phase in spiral galaxies.
Description
The emergence of a new generation of instrumentation in astrophysics, which provide spatially-resolved spectra over a large 2-dimensional (2D) field of view, offers the opportunity to perform emission-line surveys based on samples of hundreds of spectra in a 2D context, enabling us to test, confirm, and extend the previous body of results from small-sample studies based on typical long-slit spectroscopy, while at the same time opening up a new frontier of studying the 2D structure of physical and chemical properties of the disks of nearby spiral galaxies. The project developed in this dissertation represents the first endeavour to obtain full 2D coverage of the disks of a sample of spiral galaxies in the nearby universe, by the application of the Integral Field Spectroscopy (IFS) technique. The semi-continuous coverage spectra provided by this spectral imaging technique allows to study the small and intermediate linear scale variation in line emission and the gas chemistry in the whole surface of a spiral galaxy.
The PPAK IFS Nearby Galaxies Survey: PINGS, was a carefully devised observational project, designed to construct 2D spectroscopic mosaics of 17 nearby galaxies in the optical wavelength range. The sample includes different galaxy types, including normal, lopsided, interacting and barred spirals with a good range of galactic properties and star forming environments, with multi-wavelength public data. The spectroscopic data set comprises more than 50000 individual spectra, covering an observed area of nearly 100 arcmin^2, an observed surface without precedents by an IFS study. All sources of errors and uncertainties during the reduction process of the IFS observations are assessed very carefully. This methodology contributed not only to improve the standard reduction pipeline procedure for the particularly used instrument, improvements that can be applied to any similar integral-field observation and/or data reduction, but to defining a self-consistent methodology in terms of observation, data reduction and analysis for the kind of IFS surveys presented in this dissertation, as well as providing a whole new set of IFS visualization and analysis software made available for the public domain.