Analytical Core Mass Function (CMF) from Filaments: Under Which Circumstances Can Filament Fragmentation Reproduce the CMF?

Lee, Yueh-Ning; Hennebelle, P.; Chabrier, G.

doi:10.3847/1538-4357/aa898f

Cited by 34 publications

(27 citation statements)

References 103 publications

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“…This could suggest, however, that coherent density-driven filaments originate from shocks directly associated with compressive turbulence. Our results are in agreement with the gravoturbulent models of Larson (1981), Hennebelle & Chabrier (2008), and more recently Lee et al (2017) which take into account the scale dependance of the supporting thermal, turbulent, and magnetic energies. The magnetic field certainly also plays a role in the formation of large filaments, where it has been found oriented perpendicularly to nearby filaments, such as Musca and Taurus (Palmeirim et al 2013;Planck Collaboration XXXIII 2016).…”

Section: Discussionsupporting

confidence: 91%

Exposing the plural nature of molecular clouds

Robitaille

Motte

Schneider

et al. 2019

A&A

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We present the Multiscale non-Gaussian Segmentation (MnGSeg) analysis technique. This wavelet-based method combines the analysis of the probability distribution function (PDF) of map fluctuations as a function of spatial scales and the power spectrum analysis of a map. This technique allows us to extract the non-Gaussianities identified in the multiscaled PDFs usually associated with turbulence intermittency and to spatially reconstruct the Gaussian and the non-Gaussian components of the map. This new technique can be applied on any data set. In the present paper, it is applied on a Herschel column density map of the Polaris flare cloud. The first component has by construction a self-similar fractal geometry similar to that produced by fractional Brownian motion (fBm) simulations. The second component is called the coherent component, as opposed to fractal, and includes a network of filamentary structures that demonstrates a spatial hierarchical scaling (i.e. filaments inside filaments). The power spectrum analysis of the two components proves that the Fourier power spectrum of the initial map is dominated by the power of the coherent filamentary structures across almost all spatial scales. The coherent structures contribute increasingly from larger to smaller scales, without producing any break in the inertial range. We suggest that this behaviour is induced, at least partly, by inertial-range intermittency, a well-known phenomenon for turbulent flows. We also demonstrate that the MnGSeg technique is itself a very sensitive signal analysis technique that allows the extraction of the cosmic infrared background (CIB) signal present in the Polaris flare submillimetre observations and the detection of a characteristic scale for 0.1 l 0.3 pc. The origin of this characteristic scale could partly be the transition of regimes dominated by incompressible turbulence versus compressible modes and other physical processes, such as gravity.

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Section: Discussionsupporting

confidence: 91%

Exposing the plural nature of molecular clouds

Robitaille

Motte

Schneider

et al. 2019

A&A

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“…In particular, as stressed in Paper I, the high-mass part of the mass spectra tends to present a power law that is too shallow compared to the canonical Salpeter distribution. If dense clusters turn out to be assembled from material where cores are already developed, the preexisting cores may play a stronger role and the peak of the IMF could be inherited from the peak of the core mass function (CMF), as proposed theoretically in Padoan et al (1997), Hennebelle & Chabrier (2009), Hennebelle (2012), Hopkins (2012), Lee & Hennebelle (2016a), and Lee et al (2017), and suggested by simulations (Gong & Ostriker 2015;Hennebelle 2018). This picture is suggested by the observations of the CMF, which resembles the IMF (Motte et al 1998;Alves et al 2007;André et al 2010;Könyves et al 2015), and it could be the dominant mode in some environments.…”

Section: What Sets the Peak Of The Imf: Is There A Cosmic Conspiracy?mentioning

confidence: 99%

Stellar mass spectrum within massive collapsing clumps

Lee

Hennebelle

2018

A&A

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Context. Understanding the origin of the initial mass function (IMF) of stars is a major problem for the star formation process and beyond. Aim. We investigate the dependence of the peak of the IMF on the physics of the so-called first Larson core, which corresponds to the point where the dust becomes opaque to its own radiation. Methods. We performed numerical simulations of collapsing clouds of 1000 M⊙ for various gas equations of state (eos), paying great attention to the numerical resolution and convergence. The initial conditions of these numerical experiments are varied in the companion paper. We also develop analytical models that we compare to our numerical results. Results. When an isothermal eos is used, we show that the peak of the IMF shifts to lower masses with improved numerical resolution. When an adiabatic eos is employed, numerical convergence is obtained. The peak position varies with the eos, and using an analytical model to infer the mass of the first Larson core, we find that the peak position is about ten times its value. By analyzing the stability of nonlinear density fluctuations in the vicinity of a point mass and then summing over a reasonable density distribution, we find that tidal forces exert a strong stabilizing effect and likely lead to a preferential mass several times higher than that of the first Larson core. Conclusions. We propose that in a sufficiently massive and cold cloud, the peak of the IMF is determined by the thermodynamics of the high-density adiabatic gas as well as the stabilizing influence of tidal forces. The resulting characteristic mass is about ten times the mass of the first Larson core, which altogether leads to a few tenths of solar masses. Since these processes are not related to the large-scale physical conditions and to the environment, our results suggest a possible explanation for the apparent universality of the peak of the IMF.

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“…The fragmentation of purely thermal, equilibrium filaments may be expected to result in a narrow ("δ-like") prestellar CMF sharply peaked at the median thermal Jeans mass (see Lee et al 2017). However, at least two effects contribute to broadening the observed CMF.…”

Section: The Role Of Filaments In the Prestellar Cmfmentioning

confidence: 99%

The role of molecular filaments in the origin of the prestellar core mass function and stellar initial mass function

André

Arzoumanian

Könyves

et al. 2019

A&A

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Context. The origin of the stellar initial mass function (IMF) is one of the most debated issues in astrophysics. Aims. Here, we explore the possible link between the quasi-universal filamentary structure of star-forming molecular clouds and the origin of the IMF. Methods. Based on our recent comprehensive study of filament properties from Herschel Gould Belt survey observations (Arzoumanian et al.), we derive, for the first time, a good estimate of the filament mass function (FMF) and filament line mass function (FLMF) in nearby molecular clouds. We use the observed FLMF to propose a simple toy model for the origin of the prestellar core mass function (CMF), relying on gravitational fragmentation of thermally supercritical but virialized filaments. Results. We find that the FMF and the FLMF have very similar shapes and are both consistent with a Salpeter-like power-law function (dN/dlogM line ∝ M −1.5±0.1 line ) in the regime of thermally supercritical filaments (M line > 16 M /pc). This is a remarkable result since, in contrast, the mass distribution of molecular clouds and clumps is known to be significantly shallower than the Salpeter power-law IMF, with dN/dlogM cl ∝ M −0.7 cl . Conclusions. Since the vast majority of prestellar cores appear to form in thermally transcritical or supercritical filaments, we suggest that the prestellar CMF and by extension the stellar IMF are at least partly inherited from the FLMF through gravitational fragmentation of individual filaments.

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Analytical Core Mass Function (CMF) from Filaments: Under Which Circumstances Can Filament Fragmentation Reproduce the CMF?

Cited by 34 publications

References 103 publications

Exposing the plural nature of molecular clouds

Exposing the plural nature of molecular clouds

Stellar mass spectrum within massive collapsing clumps

The role of molecular filaments in the origin of the prestellar core mass function and stellar initial mass function

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