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The MPIA conference series
at Ringberg Castle
The MPIA conference series
at Ringberg Castle
 
EPoS 2020 Suggested Contribution
Link between the density/column density PDF and the stellar IMF

Yueh-Ning Lee
NTNU, Taipei, TW
In reservoir-based theories of the stellar initial mass function (IMF), lognormal density PDF is often used since it naturally results from an ISM with supersonic turbulence. However we recently showed that, in order to explain the simulation results of a top-heavy IMF (Γ ~ -0.75), a powerlaw density PDF of dV/dlog(ρ) ∝ ρ-1.5 has to be employed. The powerlaw tail of the density/column density PDF is thought to appear when the gravitational collapse is taking place, since it is observed to be associated to star-formation activities. The question then arises whether the "cores" become gravitationally bound and detach from the ambient ISM before or after the development of the powerlaw tail, i.e., when exactly a core (or a pre-core) can be delineated. The powerlaw density PDF can result both from local collapse of individual cores and the global collapse of the whole cloud. We will try to address this question by attempting to separate the contributions to the powerlaw distribution at different scales.
Caption: Left: density powerlaw PDF of the molecular cloud at several time steps. The powerlaw distribution ρ-1.5 develops very quickly after the the beginning of the simulation. Right: radial density profile around sink particles r-2. This density profile can be easily used to explain the high-density part of the measured density PDF, while it should play no role in the formation step of the prestellar cores since it is the collapse inside the core itself.
Collaborators:
H.-L. Liao, NTNU, TW
P. Hennebelle, AIM/CEA Saclay, FR
Key publication

Suggested Session: Cores