Galaxy merger morphologies and time-scales from simulations of equal-mass gas-rich disc mergers
Galaxy merger morphologies and time-scales from simulations of equal-mass gas-rich disc mergers
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DOI：
10.1111/j.1365-2966.2008.14004.x
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发表时间：
2008-05
影响因子：
4.8
通讯作者：
J. Lotz;P. Jonsson;T. J. Cox;J. Primack;National Optical Astronomy Observatory;U. California;Santa Cruz;H. C. F. Astrophysics
中科院分区：
文献类型：
--
作者：
J. Lotz;P. Jonsson;T. J. Cox;J. Primack;National Optical Astronomy Observatory;U. California;Santa Cruz;H. C. F. Astrophysics
理解星系合并率及其在星系演化中的作用的一个关键障碍是很难根据真实宇宙的瞬时快照来限制合并性质和时间尺度。识别星系合并最常见的方法是通过形态，但目前对星系扰动的时间尺度的理论计算相当粗糙。我们用蒙特卡罗辐射传输程序SUNRISE对一大套小N体/流体动力学等质量富气盘状星系合并进行了形态分析。利用得到的图像，我们考察了SDSS g带的定量形态(G，M20，C，A)与合并阶段、尘埃、视角、轨道参数、气体性质、超新星反馈和总质量的关系。我们发现，在G−M20中，合并出现最严重的扰动和不对称性，在第一次通过和最终核合并时，但在其他合并阶段可以具有正常的定量形态。合并可观测性时间尺度取决于用于识别合并的方法以及合并星系的气体分数、中心距和相对取向。增强的恒星形成高峰在强形态扰动之后和持续时间明显长于强形态扰动。尽管它们有巨大的凸起，但由于低质量恒星形成盘的存在，大多数合并残余物在g波段的光中看起来像圆盘一样，尘土飞扬。
A key obstacle to understanding the galaxy merger rate and its role in galaxy evolution is the difficulty in constraining the merger properties and time-scales from instantaneous snapshots of the real Universe. The most common way to identify galaxy mergers is by morphology, yet current theoretical calculations of the time-scales for galaxy disturbances are quite crude. We present a morphological analysis of a large suite of gadgetN-body/hydrodynamical equal-mass gas-rich disc galaxy mergers which have been processed through the Monte Carlo radiative transfer code sunrise. With the resulting images, we examine the dependence of quantitative morphology (G, M20, C, A) in the SDSS g band on merger stage, dust, viewing angle, orbital parameters, gas properties, supernova feedback and total mass. We find that mergers appear most disturbed in G−M20 and asymmetry at the first pass and at the final coalescence of their nuclei, but can have normal quantitative morphologies at other merger stages. The merger observability time-scales depend on the method used to identify the merger as well as the gas fraction, pericentric distance and relative orientation of the merging galaxies. Enhanced star formation peaks after and lasts significantly longer than strong morphological disturbances. Despite their massive bulges, the majority of merger remnants appear disc-like and dusty in g-band light because of the presence of a low-mass star-forming disc.