Stellar Mass-Gas-phase Metallicity Relation at 0.5 ≤ z ≤ 0.7: A Power Law with Increasing Scatter toward the Low-mass Regime

Yicheng Guo, David C. Koo, Yu Lu, John C. Forbes, Marc Rafelski, Jonathan R. Trump, Ricardo Amorín, Guillermo Barro, Romeel Davé, S. M. Faber, Nimish P. Hathi, Hassen Yesuf, Michael C. Cooper, Avishai Dekel, Puragra Guhathakurta, Evan N. Kirby, Anton M. Koekemoer, Pablo G. Pérez-González, Lihwai Lin, Jeffery A. NewmanJoel R. Primack, David J. Rosario, Christopher N. A. Willmer, Renbin Yan

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We present the stellar mass ({M}*)-gas-phase metallicity relation (MZR) and its scatter at intermediate redshifts (0.5≤slant z≤slant 0.7) for 1381 field galaxies collected from deep spectroscopic surveys. The star formation rate (SFR) and color at a given {M}* of this magnitude-limited (R≲ 24 AB) sample are representative of normal star-forming galaxies. For masses below 109 {M}⊙ , our sample of 237 galaxies is ˜10 times larger than those in previous studies beyond the local universe. This huge gain in sample size enables superior constraints on the MZR and its scatter in the low-mass regime. We find a power-law MZR at 108 {M}⊙ <{M}* \lt {10}11 {M}⊙ : 12+{log}(O/H)=(5.83+/- 0.19) +(0.30+/- 0.02){log}({M}*/{M}⊙ ). At 109 {M}⊙ <{M}* \lt {10}10.5 {M}⊙ , our MZR shows agreement with others measured at similar redshifts in the literature. Our power-law slope is, however, shallower than the extrapolation of the MZRs of others to masses below 109 {M}⊙ . The SFR dependence of the MZR in our sample is weaker than that found for local galaxies (known as the fundamental metallicity relation). Compared to a variety of theoretical models, the slope of our MZR for low-mass galaxies agrees well with predictions incorporating supernova energy-driven winds. Being robust against currently uncertain metallicity calibrations, the scatter of the MZR serves as a powerful diagnostic of the stochastic history of gas accretion, gas recycling, and star formation of low-mass galaxies. Our major result is that the scatter of our MZR increases as {M}* decreases. Our result implies that either the scatter of the baryonic accretion rate ({σ }\dot{M}) or the scatter of the {M}*-{M}{halo} relation ({σ }{SHMR}) increases as {M}* decreases. Moreover, our measure of scatter at z=0.7 appears consistent with that found for local galaxies. This lack of redshift evolution constrains models of galaxy evolution to have both {σ }\dot{M} and {σ }{SHMR} remain unchanged from z=0.7 to z = 0.
Original languageEnglish
Pages (from-to)103
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 11 May 2016

Keywords / Materials (for Non-textual outputs)

  • galaxies: abundances
  • galaxies: dwarf
  • galaxies: evolution
  • galaxies: formation
  • galaxies: fundamental parameters
  • galaxies: ISM


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