Two Regimes of Turbulent Fragmentation and the Stellar Initial Mass Function from Primordial to Present-Day Star Formation

By P. Padoan, Åke Nordlund, Alexei G. Kritsuk, M. Norman, P. Li. 2007

143 citations recorded by the source corpus.

The Padoan and Nordlund model of the stellar initial mass function (IMF) is derived from low-order statistics of supersonic turbulence, neglecting gravity (e.g., gravitational fragmentation, accretion, and merging). In this work, the predictions of that model are tested using the largest numerical experiments of supersonic hydrodynamic (HD) and magnetohydrodynamic (MHD) turbulence to date (~10003 computational zones) and three different codes (Enzo, Zeus, and the Stagger code). The model predicts a power-law distribution for large masses, related to the turbulence-energy power-spectrum slope and the shock-jump conditions. This power-law mass distribution is confirmed by the numerical experiments. The model also predicts a sharp difference between the HD and MHD regimes, which is recovered in the experiments as well, implying that the magnetic field, even below energy equipartition on the large scale, is a crucial component of the process of turbulent fragmentation. These results suggest that the stellar IMF of primordial stars may differ from that in later epochs of star formation, due to differences in both gas temperature and magnetic field strength. In particular, we find that the IMF of primordial stars born in turbulent clouds may be narrowly peaked around a mass of order 10 M☉, as long as the column density of such clouds is not much in excess of 1022 cm-2.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/33b72a7015243d5e00d787e48981402dca58b293

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Citations in the corpus

A comparison between grid and particle methods on the statistics of driven, supersonic, isothermal turbulence (2010, result): “These results are entirely consistent with the power law slopes obtained in Figure 2 of Padoan et al. (2007).”
The effect of magnetic fields on star cluster formation (2008, background): “…in preventing the rapid dissipation of supersonic turbulencei the absence of continued driving (Stone et al. 1998; Mac Low et al. 1998; Vazquez-Semadeni et al. 2000), though the presence of magnetic fields does change the dynamics of the turbulence (Padoan & Nordlund 2002; Padoan et al. 2007).”
Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function (2011, background): “…to super-stellar objects (Nakamura & Umemura 2001), the numerical study of supersonic hydrodynamics and magnetohydrodynamics of turbulence (Padoan et al. 2007), gradual processes behind building of a galaxy (Gibson & Matteucci 1997), the reionization of the intergalactic medium at high…”
Shocking results without shocks: Subsonic turbulence in smoothed particle hydrodynamics and moving-mesh simulations (2011, methodology): “In particular, we note that Padoan et al. (2007) observed that there appears to be a Mach number dependence of the turbulent slope in SPH, where forM = 3 a slightly steeper (and hence ‘more wrong’) slope was obtained than forM = 6.”
Turbulent molecular clouds (2012, methodology): “There is, however, a general visual trend of MHD simulations that appear more filamentary than hydrodynamical simulations (e.g. Padoan et al. 2007, Hennebelle et al. 2008).”
On the Rapid Collapse and Evolution of Molecular Clouds (2007, background): “Padoan & Nordlund (2002) and Padoan et al. (2007) discuss how magnetic turbulent compression with Kolmogorov-type scaling laws between velocity and length can partition the gas into pieces that have the Salpeter mass function at intermediate mass. Di Fazio (1986) and Elmegreen (1993, 1997)…”
ANALYTICAL THEORY FOR THE INITIAL MASS FUNCTION. II. PROPERTIES OF THE FLOW (2009, background): “…consistent explanation to why gravitational clumps obtained by taking into account purely thermal support lead to too steep an IMF at large masses (Padoan et al. 2007), while simulations which use sink particles and include by definition the turbulent support with a Kolmogorov-like power spectrum…”
The Statistics of Supersonic Isothermal Turbulence (2007, background): “At a grid resolution of 10243 points, the slopes of the power spectra in our simulations show stronger sensitivity to the numerical diffusivity of the scheme of choice than to the presence of the magnetic field (Padoan et al. 2007).”
Analytical Theory for the Initial Mass Function: CO Clumps and Prestellar Cores (2008, methodology): “Padoan et al. (2007) conclude that the CMF/IMF produced in purely hydrodynamical simulations is too stiff, compared with the Salpeter value, whereas Tilley & Pudritz (2004), performing a virial analysis, reproduce the Salpeter slope and Ballesteros-Paredes et al. (2006) find that the CMF/IMF…”
THE STAR FORMATION LAW IN NEARBY GALAXIES ON SUB-KPC SCALES (2008, unknown): “It is also likely that physical conditions inside the molecular gas change as surface densities exceed that of a typical GMC (e.g., Padoan et al. 2007).”
The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing (2008, unknown): “Padoan et al. (2007) argue that eq.”
Comparing the statistics of interstellar turbulence in simulations and observations - Solenoidal versus compressive turbulence forcing (2009, methodology): “The resolution and numerical method adopted in numerical studies of turbulence are expected to critically affect the results of the Fourier spectrum scaling within the inertial range (e.g., Klein et al. 2007; Kritsuk et al. 2007; Padoan et al. 2007).”