A Salpeter-like filament linear density function across nearby molecular clouds

TL;DR

This study finds that the distribution of filament linear densities in nearby molecular clouds follows a power law similar to the Salpeter IMF slope, suggesting a physical origin for the IMF's universality.

Contribution

It provides the first measurement of the filament linear density function across multiple molecular clouds, revealing a universal power-law distribution linked to the IMF.

Findings

The filament linear density function follows a power law with slope ~1.30-1.34.

The filament structure encodes the universal stellar initial mass function.

The results support a physical basis for IMF universality in star formation.

Abstract

The high-mass slope of the stellar initial mass function (IMF), first measured by E. Salpeter in 1955, appears universal across star-forming environments. Its origin remains a central unsolved problem in astrophysics. Using $getsf$, we measure the filament linear density function (FLDF) $-$ the mass-per-unit-length distribution of filaments $-$ across seven nearby molecular clouds (140$-$920 pc) spanning a wide range of star-forming activity. When integrated over the full hierarchy of spatial scales, the composite FLDF follows a power law with slope $\alpha \approx 1.30-1.34$, indistinguishable from Salpeter's value of $1.35$. The universal stellar mass spectrum is therefore already encoded in the hierarchical filamentary structure of the cold interstellar medium, providing a physical basis for the IMF universality assumed throughout extragalactic and cosmological astrophysics.