Galaxy Simulation with Dust Formation and Destruction
Galaxy Simulation with Dust Formation and Destruction
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DOI：
10.1093/mnras/stw3061
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发表时间：
2016-09
影响因子：
4.8
通讯作者：
S. Aoyama;K. Hou;I. Shimizu;H. Hirashita;K. Todoroki;Jun-Hwan Choi;K. Nagamine
中科院分区：
文献类型：
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作者：
S. Aoyama;K. Hou;I. Shimizu;H. Hirashita;K. Todoroki;Jun-Hwan Choi;K. Nagamine
我们对一个孤立的星系进行了平滑粒子流体动力学(SPH)模拟，并对尘埃的形成和破坏进行了新的处理。为此，我们用恒星形成和超新星反馈自我一致地处理尘埃和金属的产生。对于尘埃，我们考虑了一个简化的粒度分布模型，通过用大颗粒和小颗粒来表示整个颗粒尺寸范围。我们包括恒星喷发产生的尘埃，超新星激波(SN)造成的尘埃破坏，通过吸积和凝聚造成的颗粒生长，以及通过粉碎造成的颗粒破碎。我们发现，当星系年龄大于0.2Gyr时，固定尘埃/金属质量比的假设不再成立，此时，吸积颗粒的生长开始对尘气比的非线性上升做出贡献。正如我们在前面的单区模型中所预期的那样，粉碎通过吸积触发颗粒生长，因为它增加了颗粒的总表面积。当星系年龄大于1 Gyr时，凝聚变得很重要：在这个时期，小颗粒的丰度变得足够高，足以提高小颗粒的凝聚率。我们进一步比较了尘气比$(数学{D})$和尘埃/金属比$(数学{D}/Z)$(即耗竭)在不同年龄的径向分布与观测数据。我们发现，我们的模拟大致重现了尘气比和耗竭的径向梯度。在早期(Lesssim 0.3$Gyr)，{D}的径向梯度遵循金属丰度梯度，数学上的{D}/Z由恒星喷出物中的尘埃凝聚效率决定，而在后期，由于颗粒的吸积生长，数学上的{D}$梯度比$Z$的梯度陡峭。本文开发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。
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 We find that the assumption of fixed dust-to-metal mass ratio becomes no longer valid when the galaxy is older than 0.2 Gyr, at which point the grain growth by accretion starts to contribute to the nonlinear rise of dust-to-gas ratio.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.