The Mass Spectrum of the First Stars

TL;DR

This study uses cosmological simulations to explore the formation and mass distribution of the first stars, revealing that most stars are in the 10-100 solar mass range, with many forming in multiple systems, and their abundance patterns match observed low-metallicity stars.

Contribution

First detailed simulation-based analysis of the mass spectrum, multiplicity, and chemical signatures of the first stars in minihalos.

Findings

Two-thirds of minihalos host multiple stars.

Stars range from 1 to 300 solar masses, peaking at several tens of solar masses.

Approximately 50% of star-forming minihalos contain binary systems.

Abstract

We perform cosmological hydrodynamics simulations with non-equilibrium primordial chemistry to obtain 59 minihalos that host first stars. The obtained minihalos are used as initial conditions of local three dimensional radiation hydrodynamics simulations to investigate the formation of the first stars. We find two-thirds of the minihalos host multiple stars, while the rest of them have single stars. The mass of the stars found in our simulations are in the range of 1 Msun \la M \la 300 Msun, peaking at several x 10 Msun. Most of the very massive stars of \ga 140 Msun are born as single stars, although not all of the single stars are very massive. We also find a few stars of \la 1 Msun that are kicked by the gravitational three body interactions to the position distant from the center of mass. The frequency that a star forming minihalo contains a binary system is \sim 50%. We also investigate the abundance pattern of the stellar remnants by summing up the contributions from the first stars in the simulations. Consequently, the pattern is compatible with that of the low metallicity Damped Lyman-alpha systems or the Extremely Metal Poor (EMP) stars, if the mass spectrum obtained in our experiment is shifted to the low mass side by 0.2 dex. If we consider the case that an EMP star is born in the remnant of the individual minihalo without mixing with others, the chemical signature of the pair instability supernova is more prominent, because most of them are born as single stars.