Galactic and Magellanic Evolution with the SKA

Abstract

As we strive to understand how galaxies evolve it is crucial that we resolve physical processes and test emerging theories in nearby systems that we can observe in great detail. Our own Galaxy, the Milky Way, and the nearby Magellanic Clouds provide unique windows into the evolution of galaxies, each with its own metallicity and star formation rate. These laboratories allow us to study with more detail than anywhere else in the Universe how galaxies acquire fresh gas to fuel their continuing star formation, how they exchange gas with the surrounding intergalactic medium, and turn warm, diffuse gas into molecular clouds and ultimately stars. The λ 21-cm line of atomic hydrogen (H I) is an excellent tracer of these physical processes. With the SKA we will finally have the combination of surface brightness sensitivity, point source sensitivity and angular resolution to transform our understanding of the evolution of gas in the Milky Way, all the way from the halo down to the formation of individual molecular clouds.Advancing Astrophysics with the Square Kilometre Array

The Physics of the Cold Neutral Medium: Low-frequency Radio Recombination Lines with the Square Kilometre Array

“…A Galactic [C/H] grid can be created by comparing CRRL and HI 21 cm absorption measurements (e.g. this work; McClure-Griffiths et al 2015 in this volume). If [C/H] does not vary strongly between the HI 21 cm absorption measurements then the CRRLs can be used to also determine the CNM hydrogen density between absorption measurements.…”

“…To derive the carbon abundance and convert our carbon column densities to hydrogen column densities we aim to combine our CRRL measurements with the planned Galactic HI absorption grid survey, see McClure-Griffiths et al (2015) in this volume. We estimate that this can be done on average in the Galactic plane for about 5 extragalactic background sources per deg 2 (e.g.…”

Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era

“…3-D Faraday tomography should be done at lower frequencies (Heald et al 2015) and perfectly complements this project. SKA1 observations of HI emission in nearby galaxies (de Blok et al 2015) and in particular in the Magellanic Clouds (McClure-Griffith et al 2015) will provide data on the properties and dynamics of neutral gas. The Milky Way's magnetic field will be studied with help of the RM grid and Faraday tomography (Haverkorn et al 2015).…”

The SKA view of the Neutral Interstellar Medium in Galaxies

“…The improved capabilities of the SKA will enable these studies to be repeated but now resolving the individual gas complexes. (Equivalent absorption line studies are described in the chapters by Morganti et al 2015 andMcClure-Griffiths et al 2015. ) This should thus provide observations of a large number of galaxies at sufficient resolution to gauge the ability of and the conditions for the ISM to form GMCs over a wide range of galaxy conditions and environments.…”

“…Much progress has been made on these questions in recent years, but the required combination of column density sensitivity and high spatial resolution that is needed to definitively answer these questions has so far been missing. For example, a proper study of the first problem has so far really only been possible in the MW and the nearest galaxies in the Local Group (see the chapter by McClure-Griffiths et al 2015 elsewhere in this volume). Similarly, the second question has so far only been addressed for a limited number of galaxies with investment of a large amount of observing time.…”