# Massive Star Formation via the Collapse of Subvirial and Virialized Turbulent Massive Cores

## TL;DR

This study uses radiation hydrodynamic simulations to compare how subvirial and virialized turbulent cores influence massive star formation, core collapse dynamics, and fragmentation, revealing distinct evolutionary pathways and star formation efficiencies.

## Contribution

It provides new insights into the impact of initial core virial states on collapse behavior, accretion rates, and fragmentation in massive star formation.

## Key findings

- Subvirial cores collapse rapidly, leading to higher early accretion rates.
- Virialized cores undergo slower collapse with more fragmentation.
- Massive accretion disks become gravitationally unstable and fragment at late times.

## Abstract

Similar to their low-mass counterparts, massive stars likely form via the collapse of pre-stellar molecular cores. Recent observations suggest that most massive cores are subvirial (i.e., not supported by turbulence) and therefore are likely unstable to gravitational collapse. Here we perform radiation hydrodynamic simulations to follow the collapse of turbulent massive pre-stellar cores with subvirial and virialized initial conditions to explore how their dynamic state affects the formation of massive stars and core fragmentation into companion stars. We find that subvirial cores undergo rapid monolithic collapse resulting in higher accretion rates at early times as compared to the collapse of virialized cores that have the same physical properties. In contrast, we find that virialized cores undergo a slower, gradual collapse and significant turbulent fragmentation at early times resulting in numerous companion stars. In the absence of strong magnetic fields and protostellar outflows we find that the faster growth rate of massive stars that are born out of subvirial cores leads to an increase in the radiative heating of the core thereby further suppressing fragmentation at early times when turbulent fragmentation occurs for virialized cores. Regardless of initial condition, we find that the massive accretion disks that form around massive stars dominant the accretion flow onto the star at late times and eventually become gravitationally unstable and fragment to form companion stars at late times.