A Search For Neutral Gas Outflows In Nearby Luminous Star-Forming Galaxies

Sara Cazzoli

Departamento de Astrofísica

Año 2016

In the last decade, our understanding of the formation and evolution of galaxies over cosmic time has been significantly enhanced by large scale galaxy surveys. These surveys have drawn a detailed pic- ture of the global properties of the galaxies, establishing the galaxy stellar mass function and scaling relations (e.g., mass-metallicity).

Galaxy evolution models attempt to reproduce the properties of the galaxies and those of the surround- ing InterGalactic Medium (IGM) invoking the need of feedback mechanisms from starbursts or Active Galactic Nuclei (AGN). In fact, models of galaxy evolution without a strong (stellar or AGN) feedback, lead galaxies to have much higher Star Forming Rates (SFR) and larger stellar masses than observed. Outflows regulate Star Formation (SF) and AGN activity, and they are also considered the primary mechanism by which dust and metals are redistributed over large scales in the InterStellar Medium (ISM), or even expelled outside the galaxy into the IGM. In addition, it has been recently proposed that outflows can undergo vigorous SF. In this context, the study of the of feedback mechanisms is of critical importance to trace the build-up of stellar mass and evolution of galaxies in the Universe. Multiphase outflows are ubiquitous at any redshift. Although the bulk of the black hole growth, SF, and galaxy mergers are believed to occur at z ∼ 1-3, studies of outflows in nearby galaxies offer detailed in- sights into feedback phenomena as one of the primary drivers of galaxy evolution. In this context, local Luminous and Ultra-Luminous Infrared Galaxies ((U)LIRGs) are particularly interesting populations. On the one hand these objects show the most conspicuous cases for outflows in the local Universe. On the other hand, local (U)LIRGs have a SF-activity similar to that found for “normal” (i.e., main- sequence) high-z star forming galaxies, and share with distant galaxies some other basic structural and kinematical properties. Therefore, local (U)LIRGs allow us to study the outflow phenomenon at environments similar to those observed at high-z, but with a much higher signal-to-noise and spatial resolution. The large majority of previous outflow studies are based on long slit observations giving only a partial description of the outflow phenomenon. However, Integral Field Spectroscopy (IFS) is well suited for the spectroscopic measurement of large areas of e.g., interstellar (outflowing) gas and therefore allows to study its 2D structure.

In the present work we search for outflows in a sample of 38 local (U)LIRG systems (51 individual galaxies) with z < 0.09 observed with the VIMOS and SINFONI Integral Field Units (IFUs) of the Very Large Telescope of ESO. This allows us to extend the census of the 2D mapping of neutral winds in local (U)LIRGs, covering the less studied LIRG luminosity range. In fact, previous IFS studies are limited to a small number of extreme objects, mainly major-mergers. We exploit these optical and near-IR IFS-observations to make a significant step forwards in understanding the outflow properties such as their geometry and their connection/feedback with those of the host galaxy.

Datos de interés

Supervisores: Santiago Arribas Mocoroa (CAB), Roberto Maiolino
Universidad: Universidad Autónoma de Madrid Facultad de Ciencias; Centro de Astrobiología
Fecha de lectura: 27/05/2016