Low Masses and High Redshifts: The Evolution of the Mass-Metallicity Relation
Abstract
We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10^{8}< M/M_{\sun} < 10^{10}, obtained by stacking spectra of 83 emission-line galaxies with secure redshifts between 1.3 < z < 2.3. For these redshifts, infrared grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R23 metallicity diagnostic: ([OII]3726,3729 + [OIII] 4959,5007)/H\beta. Using spectra stacked in four mass quartiles, we find a MZ relation that declines significantly with decreasing mass, extending from 12+log(O/H) = 8.8 at M=10^{9.8} M_{\sun} to 12+log(O/H)= 8.2 at M=10^{8.2} M_{\sun}. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M>10^{9.5} M_{\sun} and z~2.3. Within the statistical uncertainties, our MZ relation agrees with the z~2.3 result, particularly since our somewhat higher metallicities (by around 0.1 dex) are qualitatively consistent with the lower mean redshift z=1.76 of our sample. For the masses probed by our data, the MZ relation shows a steep slope which is suggestive of feedback from energy-driven winds, and a cosmological downsizing evolution where high mass galaxies reach the local MZ relation at earlier times. In addition, we show that our sample falls on an extrapolation of the star-forming main sequence (the SFR-M_{*} relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high SFRs. Finally, we report no evidence for evolution of the mass-metallicity-SFR plane; our stack-averaged measurements show excellent agreement with the local relation.
Keywords
Cite
@article{arxiv.1309.4458,
title = {Low Masses and High Redshifts: The Evolution of the Mass-Metallicity Relation},
author = {Alaina Henry and Claudia Scarlata and Alberto Dominguez and Matthew Malkan and Crystal L. Martin and Brian Siana and Hakim Atek and Alejandro G. Bedregal and James W. Colbert and Marc Rafelski and Nathaniel Ross and Harry Teplitz and Andrew J. Bunker and Alan Dressler and Nimish Hathi and Daniel Masters and Patrick McCarthy and Amber Straughn},
journal= {arXiv preprint arXiv:1309.4458},
year = {2015}
}
Comments
Accepted for publication in ApJ Letters