Balance among gravitational instability, star formation and accretion determines the structure and evolution of disc galaxies
Balance among gravitational instability, star formation and accretion determines the structure and evolution of disc galaxies
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DOI：
10.1093/mnras/stt2294
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发表时间：
2013-05
影响因子：
4.8
通讯作者：
John C. Forbes;M. Krumholz;A. Burkert;A. Dekel
中科院分区：
文献类型：
--
作者：
John C. Forbes;M. Krumholz;A. Burkert;A. Dekel
在过去的 10 吉里，恒星形成星系发生了巨大的变化，从块状和富含气体的星系，变成了相当静止的、以恒星为主的盘，其特定的恒星形成率降低了几十倍。我们利用一维轴对称薄盘模拟和引力不稳定性主导的星系演化工具（GIDGET）代码的改进版本，提出了一个关于这种转变如何发生以及什么物理过程驱动它的通用理论模型。我们表明，在每个半径处，星系往往处于缓慢演化的平衡状态，其中新的吸积通过恒星形成、星系风以及由引力不稳定性（GI）驱动的扭矩通过盘的气体径向传输来平衡。气体表面密度分布取决于这些项中哪一项在给定半径处处于平衡状态——直接吸积通过恒星形成和银河系中心附近的银河风以及较大半径处的传输来平衡。我们预测星系会经历从剧烈的盘不稳定阶段到长期演化阶段的平稳过渡。该模型为z~2星系中的高速弥散和大团块、核球的生长和随后的淬灭以及局域螺旋星系中性气体剖面的特征提供了自然的解释。
Over the past 10 Gyr, star-forming galaxies have changed dramatically, from clumpy and gas rich, to rather quiescent stellar-dominated disks with specific star formation rates lower by factors of a few tens. We present a general theoretical model for how this transition occurs, and what physical processes drive it, making use of 1D axisymmetric thin disk simulations with an improved version of the Gravitational Instability-Dominated Galaxy Evolution Tool (GIDGET) code. We show that at every radius galaxies tend to be in a slowly evolving equilibrium state wherein new accretion is balanced by star formation, galactic winds, and radial transport of gas through the disk by gravitational instability (GI) -driven torques. The gas surface density profile is determined by which of these terms are in balance at a given radius - direct accretion is balanced by star formation and galactic winds near galactic centers, and by transport at larger radii. We predict that galaxies undergo a smooth transition from a violent disk instability phase to secular evolution. This model provides a natural explanation for the high velocity dispersions and large clumps in z~2 galaxies, the growth and subsequent quenching of bulges, and features of the neutral gas profiles of local spiral galaxies.