期刊
ASTROPHYSICAL JOURNAL
卷 792, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/792/1/3
关键词
galaxies: evolution; galaxies: high-redshift; ISM: abundances
In the local universe, there is good evidence that, at a given stellar mass M, the gas-phase metallicity Z is anti-correlated with the star formation rate (SFR) of the galaxies. It has also been claimed that the resulting Z(M, SFR) relation is invariant with redshift-the so-called fundamental metallicity relation (FMR). Given a number of difficulties in determining metallicities, especially at higher redshifts, the form of the Z(M, SFR) relation and whether it is really independent of redshift is still very controversial. To explore this issue at z > 2, we used VLT-SINFONI and Subaru-MOIRCS near-infrared spectroscopy of 20 zCOSMOS-deep galaxies at 2.1 < z < 2.5 to measure the strengths of up to five emission lines: [O II]lambda 3727, H beta, [O III]lambda 5007, H alpha, and [N II]lambda 6584. This near-infrared spectroscopy enables us to derive O/H metallicities, and also SFRs from extinction corrected H alpha measurements. We find that the mass-metallicity relation (MZR) of these star-forming galaxies at z approximate to 2.3 is lower than the local Sloan Digital Sky Survey (SDSS) MZR by a factor of three to five, a larger change than found by Erb et al. using [N II]/H alpha-based metallicities from stacked spectra. We discuss how the different selections of the samples and metallicity calibrations used may be responsible for this discrepancy. The galaxies show direct evidence that the SFR is still a second parameter in the MZR at these redshifts. However, determining whether the Z(M, SFR) relation is invariant with epoch depends on the choice of extrapolation used from local samples, because z > 2 galaxies of a given mass have much higher SFRs than the local SDSS galaxies. We find that the zCOSMOS galaxies are consistent with a non-evolving FMR if we use the physically motivated formulation of the Z(M, SFR) relation from Lilly et al., but not if we use the empirical formulation of Mannucci et al.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据