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Paper: Extended UV (XUV) Emission in Nearby Galaxy Disks
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 197
Authors: Gil de Paz, A.; Thilker, D.A.; Bianchi, L.; Aragón-Salamanca, A.; Boissier, S.; Madore, B.F.; Díaz-López, C.; Trujillo, I.; Pohlen, M.; Erwin, P.; Zamorano, J.; Gallego, J.; Iglesias-Páramo, J.; Vílchez, J.M.; Mollá, M.; Muñoz-Mateos, J.C.; Pérez-González, P.G.; Pedraz, S.; Sheth, K.; Kennicutt, R.C.; Swaters, R.A.; the GALEX Science Team
Abstract: We summarize the main properties of the extended UV (XUV) emission found in roughly 30% of the nearby spiral galaxies observed by the GALEX satellite. Two different classes of XUV disks are identified, the Type 1 XUV disks where significant, structured UV-bright features are found beyond the classical azimuthally-averaged star-formation threshold, and the Type 2 XUV disks, which are characterized by very extended (seven times the area where most of the stellar mass is found), blue [(FUV−K)<5mag] outer disks. These latter disks are extreme examples of galaxies growing inside-out. The few XUV disks studied in detail to date are rich in H I but relatively poor in molecular gas, have stellar populations with luminosity-weighted ages of ∼1Gyr, and ionized-gas metal abundances of ∼Z/10. As part of the CAHA-XUV project we are in the process of obtaining deep multi-wavelength imaging and spectroscopy of 65 XUV-disk galaxies so to determine whether or not these properties are common among XUV disks.
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