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arXiv 2005.11917astro-ph.GA
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星系和质量集合(GAMA):按星系类型对宇宙恒星形成历史和金属丰度演化的法医学SED重建

Galaxy And Mass Assembly (GAMA): A forensic SED reconstruction of the cosmic star formation history and metallicity evolution by galaxy type

Sabine Bellstedt, Aaron S. G. Robotham, Simon P. Driver, Jessica E. Thorne, Luke J. M. Davies, Claudia del P. Lagos, Adam R. H. Stevens, Edward N. Taylor, Ivan … 展开作者

Sabine Bellstedt, Aaron S. G. Robotham, Simon P. Driver, Jessica E. Thorne, Luke J. M. Davies, Claudia del P. Lagos, Adam R. H. Stevens, Edward N. Taylor, Ivan K. Baldry, Amanda J. Moffett, Andrew M. Hopkins, Steven Phillipps

摘要:

我们应用光谱能量分布(SED)拟合代码ProSpect的多波长成像$\sim$ 7,000星系从$z<0.06$的GAMA调查,以提取其恒星形成的历史。我们结合一个参数描述的恒星形成的历史与一个封闭的盒子中的金属丰度的演变,目前的气相金属丰度的星系是一个自由参数。我们用这种方法表明,我们能够恢复观测确定的宇宙恒星形成历史(CSFH),这表明恒星形成在宇宙的正确时代,平均而言,我们正在进行SED拟合的方式。我们还显示了贡献的CSFH的星系不同的当今视觉形态,和恒星质量。我们的分析表明,今天椭圆星系中的一半质量是在11 Gyr前。在其他形态类型中,恒星质量形成较晚,对于现在的不规则星系来说,形成时间可达6 Gyr。同样,我们样本中最大质量的星系在11 Gyr前形成了一半的恒星质量,而最小质量的星系在4 Gyr前达到了这个阶段(众所周知的“星系缩小”效应)。最后,我们的金属丰度方法使我们能够遵循星系种群气相金属丰度的平均演化,并提取恒星和气体中宇宙金属质量密度的演化,产生与宇宙中金属密度的独立,高红移观测广泛一致的结果。

英文摘要:

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.

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