The necessity of feedback physics in setting the peak of the initial mass function
The necessity of feedback physics in setting the peak of the initial mass function
复制标题
反馈物理在设置初始质量函数峰值时的必要性
DOI：
--
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
P. Hopkins
中科院分区：
文献类型：
--
作者：
D. Guszejnov;M. Krumholz;P. Hopkins
一个流行的星星形成理论是引力湍流碎裂，其中自引力结构是由引力驱动的密度波动产生的。简单的等温碎裂理论成功地再现了核心质量函数（CMF），它与恒星的初始质量函数（IMF）具有非常相似的形状。然而，等温湍流破碎的数值模拟迄今尚未成功地确定一个碎片质量尺度，是独立的模拟分辨率。此外，磁化、自引力、等温湍流的流体方程是无标度的，并且不预测任何特征质量。在本文中，我们表明，虽然一个等温的自引力流产生CMF的初始条件所施加的质量尺度，这种规模的变化作为父云的演变。此外，形成的核心会经历进一步的碎裂，并在足够长的时间后忘记它们的初始条件，产生恒星IMF的无标度纯幂律分布dN/dM <$M^（−2）。我们表明，这个问题可以通过引入额外的物理，提供了一个终止规模的级联得到缓解。我们的候选人这样的物理是一个简单的模型恒星辐射反馈。辐射加热，由吸积形成的恒星，逮捕的碎片级联，并施加一个特征的质量尺度，几乎是独立的时间演化或初始条件的恒星形成云，并同意与观察到的IMF的峰值。与此相反，模型，介绍了一个僵硬的状态方程的密度云，但不明确包括反馈的影响不产生不变的IMF。
A popular theory of star formation is gravito-turbulent fragmentation, in which self-gravitating structures are created by turbulence-driven density fluctuations. Simple theories of isothermal fragmentation successfully reproduce the core mass function (CMF) which has a very similar shape to the initial mass function (IMF) of stars. However, numerical simulations of isothermal turbulent fragmentation thus far have not succeeded in identifying a fragment mass scale that is independent of the simulation resolution. Moreover, the fluid equations for magnetized, self-gravitating, isothermal turbulence are scale-free, and do not predict any characteristic mass. In this paper we show that, although an isothermal self-gravitating flow does produce a CMF with a mass scale imposed by the initial conditions, this scale changes as the parent cloud evolves. In addition, the cores that form undergo further fragmentation and after sufficient time forget about their initial conditions, yielding a scale-free pure power-law distribution dN/dM ∝ M^(−2) for the stellar IMF. We show that this problem can be alleviated by introducing additional physics that provides a termination scale for the cascade. Our candidate for such physics is a simple model for stellar radiation feedback. Radiative heating, powered by accretion on to forming stars, arrests the fragmentation cascade and imposes a characteristic mass scale that is nearly independent of the time-evolution or initial conditions in the star-forming cloud, and that agrees well with the peak of the observed IMF. In contrast, models that introduce a stiff equation of state for denser clouds but that do not explicitly include the effects of feedback do not yield an invariant IMF.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell