Metal Abundances of KISS Galaxies. IV. Galaxian Luminosity‐Metallicity Relations in the Optical and Near‐Infrared

We explore the galaxian luminosity-metallicity (L-Z) relationship in both theoptical and the near-IR using a combination of optical photometric andspectroscopic observations from the KPNO International Spectroscopic Survey(KISS) and near-infrared photometry from the Two-micron All Sky Survey (2MASS).We supplement the 2MASS data with our own NIR photometry for a small number oflower-luminosity ELGs that are under-represented in the 2MASS database. OurB-band L-Z relationship includes 765 star-forming KISS galaxies with coarseabundance estimates from our follow-up spectra, while the correlation with KISSand 2MASS yields a total of 420 galaxies in our J-band L-Z relationship. Weexplore the effect that changing the correlation between the strong-lineabundance diagnostic R_23 and metallicity has on the derived L-Z relation. Wefind that the slope of the L-Z relationship decreases as the wavelength of theluminosity bandpass increases. We interpret this as being, at least in part, aneffect of internal absorption in the host galaxy. Furthermore, the dispersionin the L-Z relation decreases for the NIR bands, suggesting that variations ininternal absorption contribute significantly to the observed scatter. Wepropose that our NIR L-Z relations are more fundamental than the B-bandrelation, since they are largely free of absorption effects and the NIRluminosities are more directly related to the stellar mass of the galaxy thanare the optical luminosities.Comment: 22 pages, including 6 figures and 6 tables. Accepted for publication in the Astrophysical Journal (20 May 2005 issue