Metallicity Gradients and Gas Flows in Galaxy Pairs

We present the first systematic investigation into the metallicity gradients in galaxy close pairs. We determine the metallicity gradients for 8 galaxies in close pairs using HII region metallicities obtained with high signal-to-noise multi-slit observations with the Keck LRIS Spectrograph. We show that the metallicity gradients in close pairs are significantly shallower than gradients in isolated spiral galaxies such as the Milky Way, M83, and M101. These observations provide the first solid evidence that metallicity gradients in interacting galaxies are systematically different from metallicity gradients in isolated spiral galaxies. Our results suggest that there is a strong relationship between metallicity gradients and the gas dynamics in galaxy interactions and mergers.
Comment: Accepted for publication in ApJL. 6 pages, 3 figures, 1 table. Article with full resolution figures can be obtained from http://www.ifa.hawaii.edu/~kewley/Gradients.pdf