A Merger-driven Scenario for Cosmological Disk Galaxy Formation
A Merger-driven Scenario for Cosmological Disk Galaxy Formation
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DOI：
10.1086/504412
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发表时间：
2005-03
期刊：
影响因子：
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通讯作者：
B. Robertson;J. Bullock;T. J. Cox;T. Di Matteo;L. Hernquist;V. Springel;N. Yoshida
中科院分区：
文献类型：
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作者：
B. Robertson;J. Bullock;T. J. Cox;T. Di Matteo;L. Hernquist;V. Springel;N. Yoshida
ΛCDM宇宙学的等级性质给盘星系的形成带来了严重的困难。为了帮助解决这些问题，我们描述了一个新的，合并驱动的情况下，宇宙形成的盘星系在高红移，补充标准的耗散坍缩模型。在这幅图中，大的气体盘可能是由气体占主导地位的系统的高角动量合并产生的，即，在合并的高度，Mgas/（Mgas + M）<$0.5。多相ISM的加压阻止了气体在合并过程中完全转化为恒星，如果剩余足够的气体形成圆盘，残余物最终会类似于圆盘星系。我们进行星系合并的数值模拟，研究超新星反馈强度，黑洞反馈，祖气体分数，合并质量比，和轨道几何形状的影响残余磁盘的形成。我们发现，磁盘可以建立角动量通过合并和旋转的重子在残余的支持程度主要是与反馈过程相关的星星形成。在最终聚结时以气体为主的合并中，以气体为主的残余物仅限于形成。我们还表明，形成旋转支持恒星系统的合并并不限于理想化的轨道，和丰富的气体主要和次要的合并可以产生磁盘为主的恒星遗迹。我们认为，ΛCDM宇宙学的等级性质和ISM的物理学可能共同作用，通过在高红移下以气体为主的合并来建立盘的角动量，从而形成螺旋星系。
The hierarchical nature of the ΛCDM cosmology poses serious difficulties for the formation of disk galaxies. To help resolve these issues, we describe a new, merger-driven scenario for the cosmological formation of disk galaxies at high redshifts that supplements the standard dissipational collapse model. In this picture, large gaseous disks may be produced from high angular momentum mergers of systems that are gas dominated, i.e., Mgas/(Mgas + M⋆) ≳ 0.5 at the height of the merger. Pressurization from the multiphase ISM prevents the complete conversion of gas into stars during the merger, and if enough gas remains to form a disk, the remnant eventually resembles a disk galaxy. We perform numerical simulations of galaxy mergers to study how supernovae feedback strength, black hole feedback, progenitor gas fraction, merger mass ratio, and orbital geometry impact the formation of remnant disks. We find that disks can build angular momentum through mergers and the degree of rotational support of the baryons in the remnant is primarily related to feedback processes associated with star formation. Disk-dominated remnants are restricted to form in mergers that are gas dominated at the time of final coalescence. We also show that the formation of rotationally supported stellar systems in mergers is not restricted to idealized orbits, and both gas-rich major and minor mergers can produce disk-dominated stellar remnants. We suggest that the hierarchical nature of the ΛCDM cosmology and the physics of the ISM may act together to form spiral galaxies by building the angular momentum of disks through gas-dominated mergers at high redshifts.