标题： 星系多相盘中恒星形成速率的调节：热/动力学平衡模型的数值测试 显示英文标题

标题： Regulation of Star Formation Rates in Multiphase Galactic Disks: Numerical Tests of the Thermal/Dynamical Equilibrium Model

摘要： 我们使用垂直解析的数值流体动力学模拟来研究星系盘中的恒星形成和星际介质（ISM）。我们关注外盘区域，其中弥散的中性氢（HI）占主导地位，气体面密度为Sigma_SFR=3-20 Msun/kpc^2/yr，恒星加暗物质体积密度rho_sd=0.003-0.5 Msun/pc^3。恒星形成发生在非常致密、寒冷、自引力云中。由超新星事件驱动的湍流破坏了束缚云并使盘垂直膨胀。随时间变化的辐射加热（FUV）抵消了气体冷却。我们利用模拟测试一种新的自我调节恒星形成理论。与该理论一致，盘演化到一个垂直的动力学平衡和热平衡状态，同时存在温暖和冷相。恒星形成表面密度和中间平面热压力的范围是Sigma_SFR ~ 0.0001 - 0.01 Msun/kpc^2/yr 和 P_th/k_B ~ 100 -10000 cm^-3 K。与观测结果一致，湍流速度弥散约为7 km/s，总（有效）压力与热压力的比值P_tot/P_th~4-5，在整个范围内都如此。我们表明Sigma_SFR与Sigma本身没有很好的相关性，而是与Sigma*(rho_sd)^1/2相关，因为在外盘中恒星和暗物质的垂直引力占主导地位。我们还发现Sigma_SFR与P_tot有很强的几乎线性的相关性，而P_tot本身大约在动力学平衡估计值P_tot,DE的13%以内。我们发现的Sigma_SFR与湍流和热压力之间的定量关系表明，恒星形成在能量和动量产生方面效率很高，这与质量消耗的低效率形成对比。恒星形成率会调整直到在动力学时间内通过反馈补充星际介质的能量和动量损失。 显示英文摘要

摘要： We use vertically-resolved numerical hydrodynamic simulations to study star formation and the interstellar medium (ISM) in galactic disks. We focus on outer disk regions where diffuse HI dominates, with gas surface densities Sigma_SFR=3-20 Msun/kpc^2/yr and star-plus-dark matter volume densities rho_sd=0.003-0.5 Msun/pc^3. Star formation occurs in very dense, cold, self-gravitating clouds. Turbulence, driven by momentum feedback from supernova events, destroys bound clouds and puffs up the disk vertically. Time-dependent radiative heating (FUV) offsets gas cooling. We use our simulations to test a new theory for self-regulated star formation. Consistent with this theory, the disks evolve to a state of vertical dynamical equilibrium and thermal equilibrium with both warm and cold phases. The range of star formation surface densities and midplane thermal pressures is Sigma_SFR ~ 0.0001 - 0.01 Msun/kpc^2/yr and P_th/k_B ~ 100 -10000 cm^-3 K. In agreement with observations, turbulent velocity dispersions are ~7 km/s and the ratio of the total (effective) to thermal pressure is P_tot/P_th~4-5, across this whole range. We show that Sigma_SFR is not well correlated with Sigma alone, but rather with Sigma*(rho_sd)^1/2, because the vertical gravity from stars and dark matter dominates in outer disks. We also find that Sigma_SFR has a strong, nearly linear correlation with P_tot, which itself is within ~13% of the dynamical-equilibrium estimate P_tot,DE. The quantitative relationships we find between Sigma_SFR and the turbulent and thermal pressures show that star formation is highly efficient for energy and momentum production, in contrast to the low efficiency of mass consumption. Star formation rates adjust until the ISM's energy and momentum losses are replenished by feedback within a dynamical time.