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Paper: The Role of Extended Ultraviolet Disk (XUV-disk) Galaxies in the IMF Controversy
Volume: 440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function?
Page: 209
Authors: Thilker, D. A.
Abstract: The recognition of spatially extended ultraviolet disks (XUV disks) in nearly 30% of nearby spiral galaxies partially motivated recent considerations of a variable upper IMF. Most intriguing is the subset of XUV-disks which do not exhibit a comparably extended distribution of HII regions. We are attempting to improve our understanding of the XUV-disk phenomenon based on a comprehensive GALEX survey of >3000 local galaxies which examines early-type galaxies as well as spirals. We present first results from this work. Although the new survey remains in progress, one aim was to compile a statistically-significant reference sample of XUV-disk UV-emitting complexes for which the distribution function of L(Hα)/L(UV) could be measured and then compared with predictions from cluster population models incorporating stochasticity and genuine IMF variability. We also discuss HST UV-optical, Spitzer near-IR, and Magellan Hα analysis of selected XUV-disks.
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