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arXiv 1012.0277astro-ph.GAastro-ph.CO
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密度波引起的Galerkin沿Hubble序列的形态变化

Density-Wave Induced Morphological Transformation of Galaxies along the Hubble Sequence

Xiaolei Zhang, Ronald J. Buta

摘要:

在过去的二十年里,长期演化已经成为哈勃星系序列形成和演化的一个重要的新范式。一个新的动力学机制被确定,通过该机制,星系中的密度波,在非线性和全球螺旋和酒吧模式的形式,诱导重要的集体耗散效应以前未知的传统研究。这些影响导致星系盘的基本状态的演变,与典型星系的形态类型从晚期到早期哈勃类型的逐渐转变相一致。在本文中,我们回顾的理论框架,并强调我们最近的结果表明,有显着的定性和定量的差异长期演化速率预测的新理论相比,经典的方法Lynden-Bell和Kalnajs的预测。这些差异是在盘星系托管准静态,极非线性密度波模式的无碰撞冲击所发挥的主导作用的外在表现。

英文摘要:

In the past two decades, secular evolution has emerged as an important new paradigm for the formation and evolution of the Hubble sequence of galaxies. A new dynamical mechanism was identified through which density waves in galaxies, in the forms of nonlinear and global spiral and bar modes, induce important collective dissipation effects previously unknown in traditional studies. These effects lead to the evolution of the basic state of the galactic disk, consistent with the gradual transformation of a typical galaxy's morphological type from a late to an early Hubble type. In this paper, we review the theoretical framework and highlight our recent result which showed that there are significant qualitative and quantitative differences between the secular evolution rates predicted by the new theory compared with those predicted by the classical approach of Lynden-Bell and Kalnajs. These differences are the outward manifestation of the dominant role played by collisionless shocks in disk galaxies hosting quasi-stationary, extremely non-linear density-wave modes.

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