How magnetic field and stellar radiative feedback influences the collapse and the stellar mass spectrum of a massive star forming clump

TL;DR

This study uses advanced simulations to explore how magnetic fields and radiative feedback influence the initial mass function of stars in massive star-forming regions, revealing dependencies on magnetic strength and feedback efficiency.

Contribution

It introduces comprehensive numerical simulations incorporating radiative feedback and magnetic fields, along with analytical models, to analyze their effects on the stellar initial mass function.

Findings

Stellar mass spectrum varies with magnetic field strength.

The IMF shows a peak around 0.3-0.5 solar masses under certain conditions.

A universal IMF is not supported; it depends on physical parameters.

Abstract

In spite of decades of theoretical efforts, the physical origin of the stellar initial mass function (IMF) is still debated. We aim at understanding the influence of various physical processes such as radiative stellar feedback, magnetic field and non-ideal magneto-hydrodynamics on the IMF. We present a series of numerical simulations of collapsing 1000 M$_\odot$ clumps taking into account radiative feedback and magnetic field with spatial resolution down to 1 AU. Both ideal and non-ideal MHD runs are performed and various radiative feedback efficiencies are considered. We also develop analytical models that we confront to the numerical results. The sum of the luminosities produced by the stars in the calculations is computed and it compares well with the bolometric luminosities reported in observations of massive star forming clumps. The temperatures, velocities and densities are also found to be in good agreement with recent observations. The stellar mass spectrum inferred for the simulations is, generally speaking, not strictly universal and in particular varies with magnetic intensity. It is also influenced by the choice of the radiative feedback efficiency. In all simulations, a sharp drop in the stellar distribution is found at about $M_{min} \simeq$ 0.1 M$_\odot$, which is likely a consequence of the adiabatic behaviour induced by dust opacities at high densities. As a consequence, when the combination of magnetic and thermal support is not too large, the mass distribution presents a peak located at 0.3-0.5 M$_\odot$. When magnetic and thermal support are large, the mass distribution is better described by a plateau, i.e. $d N / d \log M \propto M^{-\Gamma}$, $\Gamma \simeq 0$. Abridged