论文标题
银河系和质量组装（GAMA）：宇宙星形成历史和金属性进化的法医SED重建
Galaxy And Mass Assembly (GAMA): A forensic SED reconstruction of the cosmic star formation history and metallicity evolution by galaxy type
论文作者
论文摘要
我们将频谱能量分布（SED）拟合代码前景应用于多波大成像，以$ \ sim的$ \ sim $ 7,000的GAMA调查中的$ z <0.06 $，以提取其星形形成历史。我们将恒星形成历史记录的参数描述与金属性的闭盒演变相结合，其中星系的当今气相金属性是一个自由参数。我们通过这种方法表明，我们能够恢复观察确定的宇宙恒星形成历史记录（CSFH），这表明恒星平均在宇宙的正确时期形成，以便我们进行SED拟合的方式。我们还展示了对当今视觉形态不同星系和恒星质量的星系的CSFH的贡献。我们的分析表明，当今椭圆星系中的一半质量是11 Gyr Aoto。在其他形态学类型中，恒星质量后来形成，最多6 Gyr以前，用于当今的不规则星系。同样，我们样品中最庞大的星系被证明是在11 Gyr之前形成了一半的恒星质量，而最少的巨大星系到达了4 Gyr（“ Galaxy缩减”的众所周知的效果）。最后，我们的金属性方法使我们能够遵循星系群体气相金属性的平均演化，并提取恒星和气体中宇宙金属质量密度的演化，从而与宇宙中金属密度的独立，高降低的观察结果广泛一致。
We apply the spectral energy distribution (SED) fitting code ProSpect to multiwavelength imaging for $\sim$7,000 galaxies from the GAMA survey at $z<0.06$, in order to extract their star formation histories. We combine a parametric description of the star formation history with a closed-box evolution of metallicity where the present-day gas-phase metallicity of the galaxy is a free parameter. We show with this approach that we are able to recover the observationally determined cosmic star formation history (CSFH), an indication that stars are being formed in the correct epoch of the Universe, on average, for the manner in which we are conducting SED fitting. We also show the contribution to the CSFH of galaxies of different present-day visual morphologies, and stellar masses. Our analysis suggests that half of the mass in present-day elliptical galaxies was in place 11 Gyr ago. In other morphological types, the stellar mass formed later, up to 6 Gyr ago for present-day irregular galaxies. Similarly, the most massive galaxies in our sample were shown to have formed half their stellar mass by 11 Gyr ago, whereas the least massive galaxies reached this stage as late as 4 Gyr ago (the well-known effect of "galaxy downsizing"). Finally, our metallicity approach allows us to follow the average evolution in gas-phase metallicity for populations of galaxies, and extract the evolution of the cosmic metal mass density in stars and in gas, producing results in broad agreement with independent, higher-redshift observations of metal densities in the Universe.
