The mass–metallicity relation at z ∼ 1.4 revealed with Subaru/FMOS★

Abstract

We present a stellar mass-metallicity relation at z ∼ 1.4 with an unprecedentedly large sample of ∼ 340 star-forming galaxies obtained with FMOS on the Subaru Telescope. We observed K-band selected galaxies at 1.2 ≤ z ph ≤ 1.6 in the SXDS/UDS fields with M * ≥ 10 9.5 M ⊙ , and expected F(Hα) ≥ 5 × 10 −17 erg s −1 cm −2 . Among the observed ∼ 1200 targets, 343 objects show significant Hα emission lines. The gasphase metallicity is obtained from [N ii]λ6584/Hα line ratio, after excluding possible active galactic nuclei (AGNs). Due to the faintness of the [N ii]λ6584 lines, we apply the stacking analysis and derive the mass-metallicity relation at z ∼ 1.4. Our results are compared to past results at different redshifts in the literature. The mass-metallicity relation at z ∼ 1.4 is located between those at z ∼ 0.8 and z ∼ 2.2; it is found that the metallicity increases with decreasing redshift from z ∼ 3 to z ∼ 0 at fixed stellar mass. Thanks to the large size of the sample, we can study the dependence of the mass-metallicity relation on various galaxy physical properties. The average metallicity from the stacked spectra is close to the local FMR in the higher metallicity part but > ∼ 0.1 dex higher in metallicity than the FMR in the lower metallicity part. We find that galaxies with larger E(B − V ), B − R, and R − H colours tend to show higher metallicity by ∼ 0.05 dex at fixed stellar mass. We also find relatively clearer size dependence that objects with smaller half light radius tend to show higher metallicity by ∼ 0.1 dex at fixed stellar mass, especially in the low mass part.

Galaxy metallicity scaling relations in the EAGLE simulations

“…In the following, we summarize briefly the different observational data used here (for more details, the reader is referred to the corresponding papers): de los Reyes et al (2015) (medians and scatter at z ≈ 0.8), Hunt et al (2016) (medians with 75 per cent and 25 per cent quantile levels at 0.4 < z ≤ 0.7, 0.9 < z ≤ 1.8, 1.8 < z ≤ 2.8 and 2.8 < z ≤ 3.8), Ly et al (2016) (medians with the 16th and 84th percentiles at z = 0.5-1.0), Stott et al (2013) (median values and standard errors at z ≈ 0.84-1.47), Yabe et al (2014) (medians and bootstrap errors at z ≈ 1.4), Zahid et al (2014b) (fitted metallicities and observational uncertainties at z ≈ 1.6), Wuyts et al (2016) (mean values and standard errors at z ≈ 0.9 and z ≈ 2.3), Sanders et al (2015) (mean values and uncertainties at z ≈ 2.3), Cullen et al (2014) (fitted metallicities with uncertainties at z 2), Troncoso et al (2014) (individual measurements and their uncertainties at z ≈ 3.4) and Onodera et al (2016) (results from stacking analysis at z ≈ 3.3). Dotted lines in the large four panels indicate the fits to observations at different z given by Maiolino et al (2008).…”

THE GAS INFLOW AND OUTFLOW RATE IN STAR-FORMING GALAXIES ATz∼ 1.4

“…By this threshold, the uncertainty of the reproduced flux is less than ∼10%. The details are described by Yabe et al (2012Yabe et al ( , 2014. In total, the number of the galaxy samples that we use in this work is 271.…”

Evolution of N/O abundance ratios and ionization parameters from z ∼ 0 to 2 investigated by the direct temperature method

“…Local SFGs make a tight relation in the BPT diagram, which is caused by the anticorrelation between the oxygen abundance, 12+log(O/H), and the ionization parameter, qion (Dopita & Evans 1986;Dopita et al 2000Dopita et al , 2006a. Recent studies have revealed that z ∼ 2 galaxies have [N II] λ6584/Hα (N2) values higher than those of the local SFGs for a given [O III] λ5007/Hβ (O3) on average (Shapley et al 2005;Erb et al 2006;Brinchmann et al 2008;Liu et al 2008;Kewley et al 2013b;Steidel et al 2014;Masters et al 2014;Yabe et al 2014;Hayashi et al 2015;Shapley et al 2015;Sanders et al 2016;Kashino et al 2017). The z = 2 galaxies observed in the Keck Baryonic Structure Survey (KBSS; Steidel et al 2014) show the average of ∼ 0.4 dex excesses in [N II] λ6584/Hα.…”