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arXiv 1006.4877astro-ph.CO
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DEEP2在z ~ 0.8处的质量-金属丰度和亮度-金属丰度关系

The Mass-Metallicity and Luminosity-Metallicity Relation from DEEP2 at z ~ 0.8

H. J. Zahid, L. J. Kewley, F. Bresolin

摘要:

给出了深河外星系演化探测器2(DEEP 2)巡天中1350个星系在z ~ 0.8处的质量-金属丰度(MZ)和光度-金属丰度(LZ)关系。我们确定恒星质量的光谱能量分布与当前的恒星星族合成模型拟合测光推断。这项工作使金属丰度在z ~ 0.8的星系数量增加了一个数量级以上。我们调查的MZ和LZ的关系的演变与当地的MZ和LZ的关系确定一致的方式使用~21,000星系在斯隆数字巡天。结果表明,z ~ 0.8的高恒星质量星系(log(M/M_solar)~10.6)已经达到了在局部宇宙中所看到的化学富集,而z ~ 0.8的低恒星质量星系(log(M/M_solar)~9.2)的金属丰度(Delta log(O/H)~0.15 dex)低于在局部宇宙中相同恒星质量的星系。我们发现,在z ~ 0.8和z~ 0之间,LZ关系在金属丰度和B波段光度上都发生了演化,其中B波段光度是恒星质量的函数。我们强调,在恒星形成星系的化学演化研究中,不应将B波段光度作为恒星质量的代用指标。我们的研究表明,无论是金属丰度演化和B波段光度演化的时代之间的发射线星系是恒星质量的函数,符合宇宙缩小星系演化的情况。

英文摘要:

We present the mass-metallicity (MZ) and luminosity-metallicity (LZ) relations at z ~ 0.8 from ~1350 galaxies in the Deep Extragalactic Evolutionary Probe 2 (DEEP2) survey. We determine stellar masses by fitting the spectral energy distribution inferred from photometry with current stellar population synthesis models. This work raises the number of galaxies with metallicities at z ~ 0.8 by more than an order of magnitude. We investigate the evolution in the MZ and LZ relations in comparison with local MZ and LZ relations determined in a consistent manner using ~21,000 galaxies in the Sloan Digital Sky Survey. We show that high stellar mass galaxies (log(M/M_solar)~10.6) at z ~ 0.8 have attained the chemical enrichment seen in the local universe, while lower stellar mass galaxies (log(M/M_solar)~9.2) at z ~ 0.8 have lower metallicities (Delta log(O/H)~0.15 dex) than galaxies at the same stellar mass in the local universe. We find that the LZ relation evolves in both metallicity and B-band luminosity between z ~ 0.8 and z~ 0, with the B-band luminosity evolving as a function of stellar mass. We emphasize that the B-band luminosity should not be used as a proxy for stellar mass in chemical evolution studies of star-forming galaxies. Our study shows that both the metallicity evolution and the B-band luminosity evolution for emission-line galaxies between the epochs are a function of stellar mass, consistent with the cosmic downsizing scenario of galaxy evolution.

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