论文标题
关于NGC 1052-DF2中球形簇系统的演变：动力学摩擦，球形球形相互作用和银河系潮汐
On the Evolution of the Globular Cluster System in NGC 1052-DF2: Dynamical Friction, Globular-Globular Interactions and Galactic Tides
论文作者
论文摘要
Ultra-diffuse Galaxy NGC 1052-DF2具有过多的发光球形簇（GCS），其运动学与几乎没有暗物质的存在一致。由于GC之间的速度分散与单个GC的预期内部分散相媲美，因此银河系可能高度利用GC-GC合并。如果是真的，这可以解释其GC的令人困惑的光度功能。在这里，我们通过重新构图对GC系统的三个模拟（Dutta Chowdhury等人，2019年）来检查这种可能性，在该系统中，GCS用实时GC模拟了单个颗粒。有些令人惊讶的是，我们推断出$ \ sim 0.03 \ \ rm gyr^{ - 1} $的低合并率。主要原因是GC太密集，无法在其中冲动捕获引起的潮汐冲击捕获，无法有效运行（我们推断出仅$ \ sim 0.002 \ \ rm gyr^{ - 1} $的潮汐捕获率。因此，任何合并发生的任何合并都是由其他机制驱动的，我们发现它是由动态摩擦和其他GC造成的捕获的。此处推断出的低合并率使GC的异常较大的亮度不可能由过去的GC-GC合并来解释。我们的模拟还表明，如果NGC 1052-DF2确实在很大程度上没有暗物质，那么它的潮汐场就太弱了，无法引起GC的任何重大质量损失。因此，在这种情况下，我们预测GC揭示潮汐特征是不可能的，可以通过未来的深度观察进行测试。
The ultra-diffuse galaxy NGC 1052-DF2 has an overabundance of luminous globular clusters (GCs), and its kinematics is consistent with the presence of little to no dark matter. As the velocity dispersion among the GCs is comparable to the expected internal dispersions of the individual GCs, the galaxy might be highly conducive to GC-GC merging. If true, this could explain the puzzling luminosity function of its GCs. Here, we examine this possibility by re-simulating three of our earlier simulations of the GC system (Dutta Chowdhury et al. 2019), where the GCs were modeled as single particles, with live GCs. Somewhat surprisingly, we infer a low merger rate of $\sim 0.03\ \rm Gyr^{-1}$. The main reason is that the GCs are too dense for tidal shock capture, caused by impulsive encounters among them, to operate efficiently (we infer a tidal capture rate of only $\sim 0.002\ \rm Gyr^{-1}$). Therefore, whatever mergers occur are driven by other mechanisms, which we find to be captures induced by dynamical friction and compressive tides from other GCs. The low merger rate inferred here makes it unlikely that the unusually large luminosities of the GCs can be explained as a result of past GC-GC mergers. Our simulations also indicate that, if NGC 1052-DF2 is indeed largely devoid of dark matter, its tidal field is too weak to induce any significant mass loss from the GCs. Therefore, in such a scenario, we predict that it is improbable for the GCs to reveal tidal features, something that can be tested with future deep observations.
