Metallicity Calibrations and the Mass-Metallicity Relation for Star-Forming Galaxies

Understand

(Abridged) We investigate the effect of metallicity calibrations, AGN classification, and aperture covering fraction on the local mass-metallicity (MZ) relation using 27,730 star-forming galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 4.

• We analyse the SDSS MZ relation with 10 metallicity calibrations, including theoretical and empirical methods.
• We show that the choice of metallicity calibration has a significant effect on the shape and y-intercept(12+log(O/H)) of the MZ relation.
• The absolute metallicity scale (y-int) varies up to 0.7 dex, depending on the calibration used, and the change in shape is substantial.