Monday, 8 June 2009

First direct metallicity at z>1

from Yuan & Kewley,

The authors use MOIRCS on Subaru to obtain a near-IR (rest-frame optical) spectrum of a strongly-lensed z=1.7 galaxy, and detect the [OIII] 4363A line, the first such detection at z>1. This line provides a direct measurement of the oxygen abundance; the above plot shows this measurement (red) compared to z>2 galaxies (from Erb et al.; black points) and the local relation (dashed line). While the z>2 data suggested a steeper slope in the metallicity-mass and metallicity-luminosity relations at high redshifts, with the new data point it actually doesn't look much different from at z=0. Of course, caveats about different techniques (the z>2 metallicities were not determined with the same technique) and redshifts apply.

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