Resolving The Generation of Starburst Winds in Galaxy Mergers
Resolving The Generation of Starburst Winds in Galaxy Mergers
复制标题
解决星系合并中星暴风的产生问题
DOI：
10.1093/mnras/stt690
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发表时间：
2013
影响因子：
4.8
通讯作者：
Christopher C. Hayward
中科院分区：
文献类型：
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作者：
Haverford Scholarship;P. Hopkins;D. Keres̆;N. Murray;L. Hernquist;D. Narayanan;P. Hopkins;D. Keres̆;N. Murray;L. Hernquist;Christopher C. Hayward
我们研究星系超级风驱动的主要合并，使用pc级分辨率模拟详细的恒星反馈模型，可以自我一致地遵循风的产生。这些模型包括分子冷却、巨大分子云中高密度的星星形成、超新星（I和II）的气体循环和反馈、恒星风和辐射压力。我们研究合并的系统，从小麦哲伦星云状的矮星和银河系类似物z 2星爆盘。在所有通道中都会产生多相的超级风，流出速率高达1000 M·yr^（−1）。然而，风的质量负载效率（流出率除以星星形成率，SFR）与每次合并的孤立星系类似：它更多地取决于全球星系的属性（质量，大小和逃逸速度），而不是合并的动力学状态或轨道参数。风往往是双极或单极的，但多个“事件”建立了复杂的形态与重叠，不同方向的气泡和壳在一定范围内的半径。风具有复杂的速度和相结构，物质的速度范围高达1000 km s^（−1）（形成类似哈勃的流动），以及分子、电离和热气体的混合物，这取决于星系的性质。我们研究这些不同的阶段是如何连接到不同的反馈机制。这些模拟解决了一些“次网格”模型中的问题，在这些模型中，简单的风处方可以极大地抑制合并引起的星爆，通常使得不可能形成超亮红外线星系（ULIRGs）。尽管在这里模拟的风中有大的质量载荷因子（10-20），但峰值SFR与“无风”模拟中的峰值SFR相当。风的加速作用并不相等，因此冷的致密气体仍然可以失去角动量并形成恒星，而这些恒星则会喷出最初不会参与星暴的气体。相当多的风物质并没有被束缚，在合并后的较晚时间，福尔斯会落回圆盘上，导致在恒星反馈存在的情况下，星暴后的SFR更高。我们考虑了不同的模拟数值方法及其对风相结构的影响;虽然大多数结果都是收敛的，但我们发现，在距离星系很远的外流中存在小团块对方法相当敏感。
We study galaxy superwinds driven in major mergers, using pc-scale resolution simulations with detailed models for stellar feedback that can self-consistently follow the generation of winds. The models include molecular cooling, star formation at high densities in giant molecular clouds, and gas recycling and feedback from supernovae (I and II), stellar winds and radiation pressure. We study mergers of systems from Small-Magellanic-Cloud-like dwarfs and Milky Way analogues to z ∼ 2 starburst discs. Multiphase superwinds are generated in all passages, with outflow rates up to ∼1000 M⊙ yr^(−1). However, the wind mass-loading efficiency (outflow rate divided by star formation rate, SFR) is similar to that in the isolated galaxy counterparts of each merger: it depends more on global galaxy properties (mass, size and escape velocity) than on the dynamical state or orbital parameters of the merger. Winds tend to be bi- or unipolar, but multiple ‘events’ build up complex morphologies with overlapping, differently oriented bubbles and shells at a range of radii. The winds have complex velocity and phase structure, with material at a range of speeds up to ∼1000 km s^(−1) (forming a Hubble-like flow), and a mix of molecular, ionized and hot gas that depends on galaxy properties. We examine how these different phases are connected to different feedback mechanisms. These simulations resolve a problem in some ‘subgrid’ models, where simple wind prescriptions can dramatically suppress merger-induced starbursts, often making it impossible to form Ultra Luminous Infrared Galaxies (ULIRGs). Despite large mass-loading factors (≳10–20) in the winds simulated here, the peak SFRs are comparable to those in ‘no wind’ simulations. Wind acceleration does not act equally, so cold dense gas can still lose angular momentum and form stars, while these stars blow out gas that would not have participated in the starburst in the first place. Considerable wind material is not unbound, and falls back on the disc at later times post-merger, leading to higher post-starburst SFRs in the presence of stellar feedback. We consider different simulation numerical methods and their effects on the wind phase structure; while most results are converged, we find that the existence of small clumps in the outflow at large distances from the galaxy is quite sensitive to the methodology.