Related papers: The stellar IMF at very low metallicities
We address the turbulent fragmentation scenario for the origin of the stellar initial mass function (IMF), using a large set of numerical simulations of randomly driven supersonic MHD turbulence. The turbulent fragmentation model…
We study the influence of gas metallicity, turbulence, and non-equilibrium chemistry on the evolution of the two-phase interstellar medium (warm and cold atomic phases), and thereby constrain the initial conditions for star formation…
The first Pop III stars formed out of primordial, metal free gas, in minihalos at z>20, and kickstarted the cosmic processes of reionizaton and enrichment. While these stars are likely more massive than their enriched counterparts, the…
The first generations of stars ionised and enriched their host galaxies and seeded the growth of massive black holes. Models often assume that Pop III stellar masses in different minihaloes are stochastic realisations of a single universal…
The observed stellar initial mass function (IMF) appears to vary, becoming bottom-heavy in the centres of the most massive, metal-rich early-type galaxies. It is still unclear what physical processes might cause this IMF variation. In this…
A stochastic model of fragmentation of molecular clouds has been developed for studying the resulting Initial Mass Function (IMF) where the number of fragments, inter-occurrence time of fragmentation, masses and velocities of the fragments…
We present observational evidence of the correlation between the high-mass slope of the stellar initial mass function (IMF) in young star clusters and their stellar surface density, $\sigma_{*}$. When the high-mass end of the IMF is…
(abridged version) Identifying the processes that determine the initial mass function of stars (IMF) is a fundamental problem in star formation theory. One of the major uncertainties is the exact chemical state of the star forming gas and…
As star-forming clouds collapse, the gas within them fragments to ever-smaller masses. Naively one might expect this process to continue down to the smallest mass that is able to radiate away its binding energy on a dynamical timescale, the…
The stellar initial mass function (IMF) in the early universe is essential to understand the formation of ancient galaxies. To this end, we conduct a series of long-term radiation hydrodynamic simulations following star cluster formation,…
Observational constraints on the theory of the IMF are reviewed. These observations include the new result that star formation is very rapid, usually going from start to finish in only 1 or 2 dynamical times on a wide range of scales. This…
Density probability distribution functions (PDFs) for turbulent self-gravitating clouds should be convolutions of the local log-normal PDF, which depends on the local average density rho-ave and Mach number M, and the probability…
We observe a sharp transition from a singular, high-mass mode of star formation, to a low-mass dominated mode, in numerical simulations, at a metallicity of 10^-3 Zsolar. We incorporate a new method for including the radiative cooling from…
The distribution of stellar masses that form in one star-formation event in a given volume of space is called the initial mass function (IMF). The IMF has been estimated from low-mass brown dwarfs to very massive stars. Combining IMF…
We report the stellar mass functions obtained from 20 radiation hydrodynamical simulations of star cluster formation in 500 M$_\odot$ molecular clouds with metallicities of 3, 1, 1/10 and 1/100 of the solar value, with the clouds subjected…
Any predictive theory of star formation must explain observed variations (or lack thereof) in the initial mass function. Recent work suggests that we might expect quantitative variations in the IMF as a function of metallicity (Larson 2005)…
While the stellar Initial Mass Function (IMF) appears to be close to universal within the Milky Way galaxy, it is strongly suspected to be different in the primordial Universe, where molecular hydrogen cooling is less efficient and the gas…
We present here a theoretical model to account for the stellar IMF as a result of the composite behaviour of the gas and dust distribution functions. Each of these has previously been modelled and the models tested against observations. The…
Properties of candidate stars, forming out of molecular clouds, depend on the ambient conditions of the parent cloud. We present a series of 2D and 3D simulations of fragmentation of molecular clouds in starburst regions as well as clouds…
The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing…