Using a sample of 299 H \alpha -selected galaxies at z \approx 0.8 , we study the relationship between galaxy stellar mass , gas-phase metallicity , and star formation rate ( SFR ) , and compare to previous results .
We use deep optical spectra obtained with the IMACS spectrograph at the Magellan telescope to measure strong oxygen lines .
We combine these spectra and metallicities with ( 1 ) rest-frame UV-to-optical imaging , which allows us to determine stellar masses and dust attenuation corrections , and ( 2 ) H \alpha narrowband imaging , which provides a robust measure of the instantaneous SFR .
Our sample spans stellar masses of \sim 10 ^ { 9 } to 6 \times 10 ^ { 11 } M _ { \sun } , SFRs of 0.4 to 270 M _ { \sun } yr ^ { -1 } , and metal abundances of 12 + \log ( { O / H } ) \approx 8.3 –9.1 ( \approx 0.4 –2.6 Z _ { \sun } ) .
The correlations that we find between the H \alpha -based SFR and stellar mass ( i.e. , the star-forming “ main sequence ” ) , and between the stellar mass and metallicity , are both consistent with previous z \sim 1 studies of star-forming galaxies .
We then study the relationship between the three properties using various plane-fitting techniques ( Lara-López et al . )
and a curve-fitting projection ( Mannucci et al . ) .
In all cases , we exclude strong dependence of the M _ { \star } – Z relation on SFR , but are unable to distinguish between moderate and no dependence .
Our results are consistent with previous mass-metallicity-SFR studies .
We check whether dataset limitations may obscure a strong dependence on the SFR by using mock samples drawn from the SDSS .
These experiments reveal that the adopted signal-to-noise cuts may have a significant effect on the measured dependence .
Further work is needed to investigate these results , and to test whether a “ fundamental metallicity relation ” or a “ fundamental plane ” describes star-forming galaxies across cosmic time .