Abstract
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 language | English |
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Pages (from-to) | 103 |
Journal | Astrophysical Journal |
Volume | 822 |
Issue number | 2 |
DOIs | |
Publication status | Published - 11 May 2016 |
Keywords / Materials (for Non-textual outputs)
- galaxies: abundances
- galaxies: dwarf
- galaxies: evolution
- galaxies: formation
- galaxies: fundamental parameters
- galaxies: ISM