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The Dramatic Size Evolution Of Elliptical Galaxies And The Quasar Feedback

机译：椭圆星系的剧烈尺寸演变和类星体反馈

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摘要

Observations have shown that passively evolving massive galaxies at high redshift are much more compact than local galaxies with the same stellar mass. We argue that the observed strong evolution in size is directly related to the quasar feedback, which removes huge amounts of cold gas from the central regions in a Salpeter time, inducing an expansion of the stellar distribution. The new equilibrium configuration, with a size increased by a factor (≥)3, is attained after ～40 dynamical times, corresponding to ～2 Gyr. This means that massive galaxies observed at z ≥ 1 will settle on the fundamental plane by z ～ 0.8-1. In less massive galaxies (M_4 (≤)52 × 10~(10) M_☉), the nuclear feedback is subdominant, and the mass loss is mainly due to stellar winds. In this case, the mass-loss timescale is longer than the dynamical time and results in adiabatic expansion that may increase the effective radius by a factor of up to ～2 in 10 Gyr, although a growth by a factor of (=) 1.6 occurs within the first 0.5 Gyr. Since observations are focused on relatively old galaxies, with ages (≥) Gyr, the evolution for smaller galaxies is more difficult to perceive. Significant evolution of velocity dispersion is predicted for both small and large galaxies.
机译：观测表明，在高红移下被动演化的大质量星系比恒星质量相同的局部星系要紧凑得多。我们认为观测到的大小的强演化与类星体反馈直接相关，类星体反馈在Salpeter时代从中部地区去除了大量冷气，从而导致恒星分布的扩大。经过约40次动力循环后，达到了新的平衡构型，其大小增加了（≥）3倍，相当于〜2 Gyr。这意味着在z≥1处观测到的大量星系将以z〜0.8-1沉降在基面上。在质量较小的星系（M_4（≤）52×10〜（10）M_☉）中，核反馈占主导地位，质量损失主要是由恒星风引起的。在这种情况下，质量损失的时间尺度比动态时间长，并且导致绝热膨胀，尽管发生了（=）1.6的因数增长，但绝热膨胀可能使有效半径在10 Gyr中增加高达〜2的因数。在第一个0.5 Gyr之内。由于观测集中在相对较老的星系，具有年龄（≥）Gyr，因此更难以感知较小星系的演化。预测大小星系的速度色散都会发生显着变化。

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