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arXiv 1707.07010astro-ph.GAastro-ph.COastro-ph.HEastro-ph.IMastro-ph.SR
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如何在恒星和星系形成模拟中模拟超新星

How To Model Supernovae in Simulations of Star and Galaxy Formation

Philip F. Hopkins, Andrew Wetzel, Dusan Keres, Claude-Andre Faucher-Giguere, Eliot Quataert, Michael Boylan-Kolchin, Norman Murray, Christopher C. Hayward, Kareem El-Badry

摘要:

我们研究的实施机械反馈超新星(SNe)和恒星质量损失的星系模拟中,在现实环境中的反馈(火)项目。我们提出了耦合机械反馈的FIRE-2算法,它可以应用于任何流体力学方法(如固定网格,移动网格和无网格方法),以及黑洞和恒星反馈。这种算法确保了质量、能量和动量的明显守恒,并避免了在喷出物上留下“优先方向”的印记。我们表明,它是至关重要的,将动量和热能的机械喷出物在一个自洽的方式,占SNe冷却半径时,他们没有解决。使用理想化的模拟单SN爆炸,我们表明,FIRE-2算法,独立的分辨率,再现收敛的解决方案,在能量和动量。相比之下,文献中常见的“全热”(能量转储)或“全动力学”(粒子踢)方案强烈依赖于分辨率:当应用于质量分辨率>100太阳质量时,它们会从收敛的解偏离几个数量级。在星系形成的模拟中,这种发散导致星系性质的数量级差异,除非这些模型以依赖分辨率的方式进行调整。我们表明,所有的模型,单独的时间分辨SNe收敛到消防-2解决方案在足够高的分辨率。然而,无论是在理想化的单SN模拟和宇宙学星系形成模拟,FIRE-2算法收敛速度比其他子网格模型没有重新调整参数。

英文摘要:

We study the implementation of mechanical feedback from supernovae (SNe) and stellar mass loss in galaxy simulations, within the Feedback In Realistic Environments (FIRE) project. We present the FIRE-2 algorithm for coupling mechanical feedback, which can be applied to any hydrodynamics method (e.g. fixed-grid, moving-mesh, and mesh-less methods), and black hole as well as stellar feedback. This algorithm ensures manifest conservation of mass, energy, and momentum, and avoids imprinting 'preferred directions' on the ejecta. We show that it is critical to incorporate both momentum and thermal energy of mechanical ejecta in a self-consistent manner, accounting for SNe cooling radii when they are not resolved. Using idealized simulations of single SN explosions, we show that the FIRE-2 algorithm, independent of resolution, reproduces converged solutions in both energy and momentum. In contrast, common 'fully-thermal' (energy-dump) or 'fully-kinetic' (particle-kicking) schemes in the literature depend strongly on resolution: when applied at mass resolution >100 solar masses, they diverge by orders-of-magnitude from the converged solution. In galaxy-formation simulations, this divergence leads to orders-of-magnitude differences in galaxy properties, unless those models are adjusted in a resolution-dependent way. We show that all models that individually time-resolve SNe converge to the FIRE-2 solution at sufficiently high resolution. However, in both idealized single-SN simulations and cosmological galaxy-formation simulations, the FIRE-2 algorithm converges much faster than other sub-grid models without re-tuning parameters.

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