Gemini GMOS/integral field unit spectroscopy of NGC 1569 – II. Mapping the roots of the galactic outflow |
| |
| Authors: | M S Westmoquette L J Smith J S Gallagher III and K M Exter † |
| |
| Institution: | Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT;Space Telescope Science Institute and European Space Agency, 3700 San Martin Drive, Baltimore, MD 21218, USA;Department of Astronomy, University of Wisconsin-Madison, 5534 Sterling, 475 North Charter Street, Madison, WI 53706, USA;Instituto de Astrofísca de Canarias, C/Via Lactea s/n, E38200 La Laguna, Tenerife, Spain |
| |
| Abstract: | We present a set of four Gemini-North Multi-Object Spectrograph/integral field unit (IFU) observations of the central disturbed regions of the dwarf irregular starburst galaxy NGC 1569, surrounding the well-known superstar clusters A and B. This continues on directly from a companion paper, in which we describe the data reduction and analysis techniques employed and present the analysis of one of the IFU pointings. By decomposing the emission-line profiles across the IFU fields, we map out the properties of each individual component identified and identify a number of relationships and correlations that allow us to investigate in detail the state of the ionized interstellar medium (ISM). Our observations support and expand on the main findings from the analysis of the first IFU position, where we conclude that a broad (?400 km s?1) component underlying the bright nebular emission lines is produced in a turbulent mixing layer on the surface of cool gas knots, set up by the impact of the fast-flowing cluster winds. We discuss the kinematic, electron-density and excitation maps of each region in detail and compare our results to previous studies. Our analysis reveals a very complex environment with many overlapping and superimposed components, including dissolving gas knots, rapidly expanding shocked shells and embedded ionizing sources, but no evidence for organized bulk motions. We conclude that the four IFU positions presented here lie well within the starburst region where energy is injected, and, from the lack of substantial ordered gas flows, within the quasi-hydrostatic zone of the wind interior to the sonic point. The net outflow occurs at radii beyond 100–200 pc, but our data imply that mass-loading of the hot ISM is active even at the roots of the wind. |
| |
| Keywords: | ISM: kinematics and dynamics galaxies: evolution galaxies: individual: NGC 1569 galaxies: ISM galaxies: starburst |
|
|
