An Explanation for the Observed Weak Size Evolution of Disk Galaxies
An Explanation for the Observed Weak Size Evolution of Disk Galaxies
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DOI：
10.1086/523661
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发表时间：
2006-12
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通讯作者：
R. Somerville;M. Barden;H. Rix;E. Bell;S. Beckwith;A. Borch;J. Caldwell;B. Haeussler;C. Heymans;K. Jahnke;S. Jogee;D. H. Mcintosh;K. Meisenheimer;C. Peng;S. Sánchez;L. Wisotzki;C. Wolf
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作者：
R. Somerville;M. Barden;H. Rix;E. Bell;S. Beckwith;A. Borch;J. Caldwell;B. Haeussler;C. Heymans;K. Jahnke;S. Jogee;D. H. Mcintosh;K. Meisenheimer;C. Peng;S. Sánchez;L. Wisotzki;C. Wolf
用哈勃太空望远镜和地面观测遥远的星系表明，从z∼1到现在，星系盘的径向大小和恒星质量之间的关系只有轻微的演变。利用斯隆数字天空调查(SDSS)附近盘状星系的样本和GEMS(银河系演化自形态和SEDS)调查的高红移数据，我们调查了这一结果是否与结构形成的分层范式下的理论预期一致。在Λ的清洁发展机制模型中，暗物质晕的维里半径和质量之间的关系在这个时间间隔内演化了大约2倍。然而，N体模拟已经表明，给定质量的晕在高红移时具有较不集中的质量轮廓。当我们计算预期的盘大小-恒星质量分布时，考虑到暗物质晕内部结构的这种演化以及坍塌重子的自引力对暗物质的绝热收缩，我们发现自z∼1以来在固定恒星质量下预测的平均尺寸的演化约为15%-20%，与来自宝石的观测约束很好地一致。在红移z∼2，该模型预测，固定恒星质量的圆盘平均只有今天的60%大。类似地，我们预测在给定恒星质量(本质上是塔利-费雪关系的零点)时，z∼1的自转速度仅比现在大约10%(z∼2时为20%)。
Surveys of distant galaxies with the Hubble Space Telescope and from the ground have shown that there is only mild evolution in the relationship between radial size and stellar mass for galactic disks from z ∼ 1 to the present day. Using a sample of nearby disk-dominated galaxies from the Sloan Digital Sky Survey (SDSS) and high-redshift data from the GEMS (Galaxy Evolution from Morphology and SEDs) survey, we investigate whether this result is consistent with theoretical expectations within the hierarchical paradigm of structure formation. The relationship between virial radius and mass for dark matter halos in the ΛCDM model evolves by about a factor of 2 over this interval. However, N-body simulations have shown that halos of a given mass have less centrally concentrated mass profiles at high redshift. When we compute the expected disk size-stellar mass distribution, accounting for this evolution in the internal structure of dark matter halos and the adiabatic contraction of the dark matter by the self-gravity of the collapsing baryons, we find that the predicted evolution in the mean size at fixed stellar mass since z ∼ 1 is about 15%-20%, in good agreement with the observational constraints from GEMS. At redshift z ∼ 2, the model predicts that disks at fixed stellar mass were on average only 60% as large as they are today. Similarly, we predict that the rotation velocity at a given stellar mass (essentially the zero point of the Tully-Fisher relation) is only about 10% larger at z ∼ 1 (20% at z ∼ 2) than at the present day.