Structure and Star Formation in Galaxies out to z = 3: Evidence for Surface Density Dependent Evolution and Upsizing
Structure and Star Formation in Galaxies out to z = 3: Evidence for Surface Density Dependent Evolution and Upsizing
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DOI：
10.1086/592431
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
M. Franx;P. V. van Dokkum;N. F. Schreiber;S. Wuyts;I. Labbé;S. Toft
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文献类型：
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作者：
M. Franx;P. V. van Dokkum;N. F. Schreiber;S. Wuyts;I. Labbé;S. Toft
我们对CDF南部的星系进行了分析。我们发现，在给定的质量下，颜色和大小之间存在着z=3的密切关系，其中红色星系较小，蓝色星系较大。我们发现，这种关系是由恒星面密度或推断的速度色散驱动的：面密度高的星系是红色的，比恒星形成率低，而面密度低的星系是蓝色的，比恒星形成率高。比起恒星质量，表面密度和推算的速度色散与特定恒星形成率和颜色的相关性更好。因此，恒星质量本身并不能很好地预测星系的恒星形成历史。一般来说，具有给定表面密度的星系在红移较高时具有较高的比恒星形成率。具体地说，面密度为(1-3)×109M的☉kpc−2星系在低红移时是“红色的和死亡的”，大约50%的星系在z=1处形成恒星，几乎所有的星系都在z=2处形成恒星。这为星系向红色序列的晚期演化提供了直接的补充证据。具有给定质量的星系的大小演化为1/(1+z)0.59±0.10。因此，星系在其历史上经历了显著的增大。质量最高的星系和静止星系的大小演化速度最快。从z=0到z=2.5的结构关系的持续存在，以及星系的扩大意味着，从z=2.5到z=2.5，甚至更高的范围内，存在着类似于哈勃序列的关系。Z⩾1.5时的恒星形成星系与z=0时的恒星形成星系有很大的不同，因为它们可能有非常高的气体分数，恒星形成的时间尺度与轨道时间相当。
We present an analysis of galaxies in the CDF-South. We find a tight relation to z = 3 between color and size at a given mass, with red galaxies being small, and blue galaxies being large. We show that the relation is driven by stellar surface density or inferred velocity dispersion: galaxies with high surface density are red and have low specific star formation rates, and galaxies with low surface density are blue and have high specific star formation rates. Surface density and inferred velocity dispersion are better correlated with specific star formation rate and color than stellar mass. Hence stellar mass by itself is not a good predictor of the star formation history of galaxies. In general, galaxies at a given surface density have higher specific star formation rates at higher redshift. Specifically, galaxies with a surface density of (1–3) × 109 M☉ kpc−2 are “red and dead” at low redshift, approximately 50% are forming stars at z = 1, and almost all are forming stars by z = 2. This provides direct additional evidence for the late evolution of galaxies onto the red sequence. The sizes of galaxies at a given mass evolve like 1/(1 + z)0.59 ± 0.10. Hence galaxies undergo significant upsizing in their history. The size evolution is fastest for the highest mass galaxies and quiescent galaxies. The persistence of the structural relations from z = 0 to z = 2.5, and the upsizing of galaxies imply that a relation analogous to the Hubble sequence exists out to z = 2.5, and possibly beyond. The star-forming galaxies at z ⩾ 1.5 are quite different from star-forming galaxies at z = 0, as they have likely very high gas fractions, and star formation timescales comparable to the orbital time.