LOW MASSES AND HIGH REDSHIFTS: THE EVOLUTION OF THE MASS-METALLICITY RELATION
- Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States)
- Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States)
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521 (United States)
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095 (United States)
- Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
- Laboratoire d'astrophysique, École Polytechniuqe Fédérale de Lausanne, Observatoire de Sauverny, 1290 Versoix (Switzerland)
- Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
- Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States)
- Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, OX1 3RH (United Kingdom)
- Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States)
We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10{sup 8} ∼< M/M {sub ☉} ∼< 10{sup 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 R {sub 23} metallicity diagnostic: ([O II] λλ3726, 3729 + [O III] λλ4959, 5007)/Hβ. 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{sup 9.8} M {sub ☉}, to 12+log(O/H) = 8.2 at M = 10{sup 8.2} M {sub ☉}. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M ∼> 10{sup 9.5} M {sub ☉} 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 {sub *} relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high star formation rates (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.
- OSTI ID:
- 22215422
- Journal Information:
- Astrophysical Journal Letters, Vol. 776, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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