The Study of Nebular Emission on Nearby Spiral Galaxies in the IFU Era

A new generation of wide-field emission-line surveys based on integral field units (IFU) is allowing us to obtain spatially resolved information of the gas-phase emission in nearby late-type galaxies, based on large samples of HII regions and full two-dimensional coverage.These observations are allowing us to discover and characterise abundance differentials between galactic substructures and new scaling relations with global physical properties. Here I review some highlights of our current studies employing this technique: (1) the case study of NGC 628, the largest galaxy ever sampled with an IFU; (2) a statistical approach to the abundance gradients of spiral galaxies, which indicates a universal radial gradient for oxygen abundance; and (3) the discovery of a new scaling relation of HII regions in spiral galaxies, the local mass-metallicity relation of star-forming galaxies. The observational properties and constrains found in local galaxies using this new technique will allow us to interpret the gas-phase abundance of analogue high-z systems.Comment: Review article to appear in: "Metals in 3D: A Cosmic View from Integral Field Spectroscopy", Advances in Astronomy, Hindawi Publishing Corporatio

Geografía de la Gobernanza. Dinámicas multiescalares de los procesos económico-ambientales (Reseña)

Para el conjunto de autores que participan en este libro, la gobernanza se analiza como un proceso para la definición democrática de objetivos de interés público y la implementación participativa de medidas para alcanzarlos. En este contexto, se reconocen explícitamente los conflictos y tensiones a raíz de intereses contrapuestos; pero al mismo tiempo se destaca la necesidad de expresar y negociar dichos intereses no sólo en el ámbito administrativo-institucional formalmente establecido, sino también mediante diferentes plataformas fuera de la influencia directa de las instituciones gubernamentales. Los autores estudian, desde una perspectiva interdisciplinaria, las relaciones de negociación entre múltiples actores como consecuencia de la intersección entre diversas escalas (local, regional, nacional e internacional) y diversos ámbitos del mundo económico-social, ya sean certificaciones para ciertos productos y servicios, cadenas globales de producción agrícola o manufacturera o pagos por servicios ambientales. El entrecruzamiento de estas temáticas (escalas y ámbito socio-económico) permitió desarrollar un análisis complejo y dinámico de las formas de organización económico-social de los territorios, así como abordar uno de los dilemas actuales de las ciencias sociales: la combinación entre procesos sistémico-globales y las particularidades de cada territorio. El análisis de la acción económica y política como proceso contextualizado espacial y temporal, implica que el análisis de la gobernanza desde una perspectiva geográfica se interese en el proceso dinámico y flexible de la interrelación entre el ambiente institucional y los arreglos institucionales. De esta forma, tanto los procesos socio-políticos que operan en diferentes escalas, como las formas de coordinación y regulación de las economías y recursos naturales regionales y locales, permiten comprender que el desarrollo económico y ambiental de los territorios investigados en esta obra es mucho más que el resultado de las fuerzas del mercado

Multi-dimensional analysis of the chemical and physical properties of spiral galaxies

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.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.National Council for Science and Technology (CONACYT, Mexico), Dirección General de Relaciones Internacionales (SEP, Mexico), Trinity College, the Cambridge Philosophical Society, and the Royal Astronomical Society

The oxygen abundance in the IFU era

Spatially-resolved information of gas-phase emission provided by integral field units (IFUs) are allowing us to perform a new generation of emission-line surveys, based on large samples of HII regions and full two-dimensional coverage. Here we present two highlights of our current studies employing this technique: 1) A statistical approach to the abundance gradients of spiral galaxies, which indicates an -universal- radial gradient for oxygen abundance; and 2) The discovery of a new scaling relation of HII regions in spiral galaxies, the "local" mass-metallicity relation of star-forming galaxies.Comment: 6 pages, to appear in Highlights of Spanish Astrophysics VII, Proceedings of the X Scientific Meeting of the Spanish Astronomical Society held on July 9-13, 2012, in Valencia, Spai

Inner and outer star forming regions over the disks of spiral galaxies. I. Sample characterization

Context. The knowledge of abundance distributions is central to understanding the formation and evolution of galaxies. Most of the relations employed for the derivation of gas abundances have so far been derived from observations of outer disk HII regions, despite the known differences between inner and outer regions. Aims. Using integral field spectroscopy (IFS) observations we aim to perform a systematic study and comparison of two inner and outer HII regions samples. The spatial resolution of the IFS, the number of objects and the homogeneity and coherence of the observations allow a complete characterization of the main observational properties and differences of the regions. Methods. We analyzed a sample of 725 inner HII regions and a sample of 671 outer HII regions, all of them detected and extracted from the observations of a sample of 263 nearby, isolated, spiral galaxies observed by the CALIFA survey. Results. We find that inner HII regions show smaller equivalent widths, greater extinction and luminosities, along with greater values of [NII]{\lambda}6583/H{\alpha} and [OII]{\lambda}3727/[OIII]{\lambda}5007 emission-line ratios, indicating higher metallicites and lower ionization parameters. Inner regions have also redder colors and higher photometric and ionizing masses, although Mion/Mphot is slighty higher for the outer regions. Conclusions. This work shows important observational differences between inner and outer HII regions in star forming galaxies not previously studied in detail. These differences indicate that inner regions have more evolved stellar populations and are in a later evolution state with respect to outer regions, which goes in line with the inside-out galaxy formation paradigm.Comment: 16 page