# GMC Collisions As Triggers of Star Formation. IV. The Role of Ambipolar Diffusion

## TL;DR

This study uses 3D magnetohydrodynamic simulations to explore how ambipolar diffusion influences star formation in colliding giant molecular clouds, revealing that AD enhances dense core formation especially in stronger magnetic fields.

## Contribution

The paper introduces extended simulations incorporating ambipolar diffusion in GMC collisions, demonstrating its significant role in dense core formation under certain magnetic conditions.

## Key findings

- AD modestly affects weak-field GMC collisions
- AD significantly promotes dense core formation in strong-field cases
- Core formation efficiency increases from 0.2% to 2% with AD

## Abstract

We investigate the role of ambipolar diffusion (AD) in collisions between magnetized giant molecular clouds (GMCs), which may be an important mechanism for triggering star cluster formation. Three dimensional simulations of GMC collisions are performed using a version of the Enzo magnetohydrodynamics code that has been extended to include AD. The resistivities are calculated using the 31-species chemical model of Wu et al. (2015). We find that in the weak-field, $10\:{\rm \mu G}$ case, AD has only a modest effect on the dynamical evolution during the collision. However, for the stronger-field, $30\:{\rm \mu G}$ case involving near-critical clouds, AD results in formation of dense cores in regions where collapse is otherwise inhibited. The overall efficiency of formation of cores with $n_{\rm H}\geq10^{6}\:{\rm cm}^{-3}$ in these simulations is increases from about 0.2% to 2% once AD is included, comparable to observed values in star-forming GMCs. The gas around these cores typically has relatively slow infall at speeds that are a modest fraction of the free-fall speed.