PI: Jonathan Heiner, Universite Laval, firstname.lastname@example.org
Address: Department of Physics, Quebec, G1K 7P4, Canada
CoI: Gerhardt Meurer, University of Western Australia
CoI: Jessica Werk, UC Santa Cruz
CoI: Ron Allen, Space Telescope Science Institute
Title: Metals and molecules in HI-selected galaxies
Abstract: We will obtain strong emission line spectra across several galaxy disks. These galaxies, despite having been observed at multiple wavelengths (UV, Halpha, HI), lack a solid measure of spatially resolved metal abundances. Our proposed observations will yield the first measurements of the metal abundance and reddening gradients in these sources. These gradients are the main ingredient in our primary goal: to test the theory that much, or most, of the observed HI in galaxies originates from H2 in large photo-dissociation regions (PDRs). How much HI is produced depends on the local UV radiation field, but is also extremely sensitive to the local metal content of the ISM. From this, we can test our PDR models and provide upper limits to the H2 content, which is almost impossible to observe directly, even in our (still relatively nearby) sample of galaxies. The resulting total gas (and molecular) profile will be tested for consistency with other measures of the gas, such as dynamical properties, CO observations and extinction properties. This dataset will also be useful for examining biases in large spectroscopic surveys (like SDSS), where fibers sample the central portion of each galaxy only, and greatly increase currently available abundance gradients of galaxies.
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