2015/10/31 by Dávid Guszejnov, David Guszejnov, Mark R. Krumholz +1 · 61 citations
Physics and Astronomy · #Accretion (finance) #Astrophysics #Astrophysics and Star Formation Studies #Fragmentation (computing) #Galaxy #Initial mass function #Isothermal process #Mass distribution #Mechanics #Molecular cloud #Physics #Quantum mechanics #Radiative transfer #Solar and Space Plasma Dynamics #Star formation #Stars #Statistical physics #Stellar, planetary, and galactic studies #Thermodynamics #Turbulence #astro-ph.CO #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stw315
published in Monthly Notices of the Royal Astronomical Society 458(1), 673-680 (Oxford University Press) · 9 pages, 4 figures
arxiv created 2016/01/20 · openalex publication_date 2016/02/10 · arxiv updated 2018/04/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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.