arXiv 1609.075472016-09astro-ph.GA

尘埃形成和破坏的星系模拟

Galaxy Simulation with Dust Formation and Destruction

Shohei Aoyama, Kuan-Chou Hou, Ikkoh Shimizu, Hiroyuki Hirashita, Keita Todoroki, Jun-Hwan Choi, Kentaro Nagamine

备注：: 18 pages, 16 figures, published on MNRAS
发表信息：: MNRAS (2017) 466 (1): 105-121
DOI：: 10.1093/mnras/stw3061

摘要：

我们进行平滑粒子流体动力学（SPH）模拟一个孤立的星系与新的治疗尘埃的形成和破坏。为此，我们将尘埃和金属的产生与恒星的形成和超新星的反馈相一致。对于灰尘，我们认为一个简化的模型的粒度分布，代表整个范围内的粒度与大颗粒和小颗粒。我们包括恒星喷出物中的尘埃产生，超新星（SN）冲击造成的尘埃破坏，吸积和凝聚造成的颗粒生长，以及破碎造成的颗粒破坏。我们发现，当星系年龄超过0.2 Gyr时，固定的尘埃-金属质量比的假设不再有效，此时吸积颗粒的生长开始有助于尘埃-气体比的非线性上升。正如我们之前的单区模型所预期的那样，破碎通过吸积触发晶粒生长，因为它增加了晶粒的总表面积。当星系的年龄大于$\sim$ 1 Gyr时，凝结作用就变得很明显：在这个时期，小颗粒的丰度变得足够高，从而提高了小颗粒的凝结速度。我们进一步比较了粉尘-气体比$(\mathcal{D})$和粉尘-金属比$(\mathcal{D}/Z)$的径向分布（即，在不同的年龄段与观察数据。我们发现，我们的模拟广泛地再现了径向梯度的尘气比和耗尽。在早期阶段（$\lesssim 0.3$ Gyr），$\mathcal{D}$的径向梯度遵循金属丰度梯度，$\mathcal{D}/Z$由恒星喷出物中尘埃的凝聚效率决定，而在后期阶段，由于吸积作用导致的颗粒生长，$\mathcal{D}$的径向梯度比$Z$的径向梯度更陡。本文提出的框架适用于任何基于SPH的星系演化模拟，包括宇宙学模拟。

英文摘要：

We perform smoothed particle hydrodynamics (SPH) simulations of an isolated galaxy with a new treatment for dust formation and destruction. To this aim, we treat dust and metal production self-consistently with star formation and supernova feedback. For dust, we consider a simplified model of grain size distribution by representing the entire range of grain sizes with large and small grains. We include dust production in stellar ejecta, dust destruction by supernova (SN) shocks, grain growth by accretion and coagulation, and grain disruption by shattering. We find that the assumption of fixed dust-to-metal mass ratio becomes no longer valid when the galaxy is older than 0.2 Gyr, at which point the grain growth by accretion starts to contribute to the nonlinear rise of dust-to-gas ratio. As expected in our previous one-zone model, shattering triggers grain growth by accretion since it increases the total surface area of grains. Coagulation becomes significant when the galaxy age is greater than $\sim$ 1 Gyr: at this epoch the abundance of small grains becomes high enough to raise the coagulation rate of small grains. We further compare the radial profiles of dust-to-gas ratio $(\mathcal{D})$ and dust-to-metal ratio $(\mathcal{D}/Z)$ (i.e., depletion) at various ages with observational data. We find that our simulations broadly reproduce the radial gradients of dust-to-gas ratio and depletion. In the early epoch ($\lesssim 0.3$ Gyr), the radial gradient of $\mathcal{D}$ follows the metallicity gradient with $\mathcal{D}/Z$ determined by the dust condensation efficiency in stellar ejecta, while the $\mathcal{D}$ gradient is steeper than the $Z$ gradient at the later epochs because of grain growth by accretion. The framework developed in this paper is applicable to any SPH-based galaxy evolution simulations including cosmological ones.

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：

相关论文