Gemini GMOS/IFU spectroscopy of NGC 1569 - I: Mapping the properties of a young star cluster and its environment

Abstract

[Abridged] We present Gemini-North GMOS/IFU observations of a young star cluster (cluster 10) and its environment near the centre of the dwarf irregular starburst galaxy NGC 1569. This forms part of a larger and on-going study of the formation and collimation mechanisms of galactic winds, including three additional IFU pointings in NGC 1569 covering the base of the galactic wind which are analysed in a companion paper. The good spatial- and spectral-resolution of these GMOS/IFU observations, covering 4740-6860 A, allow us to probe the interactions between clusters and their environments on small scales. Combining our GMOS spectrum with HST imaging, we find that cluster 10 is composed of two very close components with ages of 5-7 Myr and <5 Myr, and a combined mass of 7 +/- 5 x 10^3 Msun. A detailed analysis of the H_alpha emission line profile shapes across the whole field-of-view shows them to be composed of a bright narrow feature (intrinsic FWHM ~ 50 km/s) superimposed on a fainter broad component (FWHM < 300 km/s). By mapping the properties of each individual component, we investigate the small-scale structure and properties of the ionized ISM, including reddening, excitation and electron densities, and for the first time find spatial correlations between the line component properties. We discuss in detail the possible mechanisms that could give rise to the two components and these correlations, and conclude that the most likely explanation for the broad emission is that it is produced in a turbulent mixing layer on the surface of the cool gas clumps embedded within the hot, fast-flowing cluster winds. We conclude we are sampling well within the outer bounding shocks of the expanding superbubbles and within the outflow 'energy injection zone'.

22 pages, 14 figures, 4 tables, accepted to MNRAS

References in corpus (5)

• On the feedback from super stellar clusters. I. The structure of giant HII regions and HII galaxies
• The Massive Star Population in the Giant HII Region Tol89 in NGC5398
• 3D Spectroscopy of Blue Compact Galaxies. Diagnostic Diagrams
• The Starburst-Interstellar Medium Interaction in NGC 1569 II. Small-Scale Examination of Nebular Emission, H II Region Size Distribution, and H II Region Luminosity Function
• Distribution of extinction and star formation in NGC1569

Cited by in corpus (6)

• The SINS Survey: Broad Emission Lines in High-Redshift Star-Forming Galaxies
• The turbulent destruction of clouds - I. A k-epsilon treatment of turbulence in 2D models of adiabatic shock-cloud interactions
• Studying the galactic outflow in NGC 1569
• The Stellar and Gas Kinematics of the LITTLE THINGS Dwarf Irregular Galaxy NGC 1569
• Numerical simulations of shocks encountering clumpy regions
• Filaments in Galactic Winds Driven by Young Stellar Clusters