arXiv 1505.079102015-05-29astro-ph.GA

第一次看到银河飞行的互动。II。Flybys重要吗？

A First Look at Galaxy Flyby Interactions. II. Do Flybys matter?

Manodeep Sinha, Kelly Holley-Bockelmann

备注：: Figure 5 and Figure 7 show the two key results of the paper. Submitted to ApJ, comments are welcome

摘要：

在本系列的第二篇论文中，我们提出了来自宇宙学模拟的结果，对飞越相互作用的人口统计，以衡量其对星系演化的潜在影响。在以前的一篇论文中，我们证明了飞越-两个独立的光环相互渗透但在稍后的时间分离并且不合并的相互作用-比以前认为的更频繁地发生。特别是，我们发现，在低的红移，飞掠的频率增加，是可比的，甚至大于合并的晕$\gtrsim 10^{11} M_\odot/h$的频率。在本文中，我们分类飞掠根据其轨道和水平的扰动上所涉及的晕。我们发现，大多数的飞掠穿透深度比$\sim R_{half}$的主要和有一个初始的相对速度$\sim 1.6\times V_{vir}$的主要。在高$z$时，所有晕的典型飞越质量比为$\sim 0.1$，而在低$z$时，大量的初级晕与小的次级晕进行飞越。我们估计的扰动从飞越的主要和次要的，并发现一个典型的飞越主要是非微扰的主晕。然而，由于一个巨大的主经历这么多的飞越在任何给定的时间，他们几乎不断的扰动事件的受害者。特别是，我们发现的flybys，导致$\sim 1\%$的结合能的初级晕发生$\gtrsim 1 $ Gyr $^{-1}$晕$> 10^{10} M_\odot/h$为$z \lesssim 4$。次级晕，另一方面，是高度扰动的典型遭遇，经历了一个变化的结合能的近秩序单位。我们的研究结果表明，在中等到较低的红移（$z \lesssim 4$）下，飞越可以驱动星系转变的重要部分。我们触及的影响，观测调查，质光比，星系组装偏差。

英文摘要：

In the second paper of this series, we present results from cosmological simulations on the demographics of flyby interactions to gauge their potential impact on galaxy evolution. In a previous paper, we demonstrated that flybys -- an interaction where two independent halos inter-penetrate but detach at a later time and do not merge -- occur much more frequently than previously believed. In particular, we found that the frequency of flybys increases at low redshift and is comparable to or even greater than the frequency of mergers for halos $\gtrsim 10^{11} M_\odot/h$. In this paper, we classify flybys according to their orbits and the level of perturbation exacted on both the halos involved. We find that the majority of flybys penetrate deeper than $\sim R_{half}$ of the primary and have an initial relative speed $\sim 1.6\times V_{vir}$ of the primary. The typical flyby mass-ratio is $\sim 0.1$ at high $z$ for all halos, while at low $z$, massive primary halos undergo flybys with small secondary halos. We estimate the perturbation from the flyby on both the primary and the secondary and find that a typical flyby is mostly non-perturbative for the primary halo. However, since a massive primary experiences so many flybys at any given time, they are nearly continually a victim of a perturbative event. In particular, we find flybys that cause $\sim 1\%$ change in the binding energy of a primary halo occurs $\gtrsim 1 $ Gyr$^{-1}$ for halos $> 10^{10} M_\odot/h$ for $z \lesssim 4$. Secondary halos, on the other hand, are highly perturbed by the typical encounter, experiencing a change in binding energy of nearly order unity. Our results imply that flybys can drive a significant part of galaxy transformation at moderate to lower redshifts ($z \lesssim 4$). We touch on implications for observational surveys, mass-to-light ratios, and galaxy assembly bias.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

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