Simulations of un-equal binary collisions embedded in a turbulent gas cloud far away of a massive gravitational center

TL;DR

This study uses simulations to analyze the dynamics of unequal binary collisions within a turbulent gas cloud, considering different energy ratios and external gravitational influences to understand collapse behaviors.

Contribution

It introduces a detailed simulation framework for unequal binary collisions in turbulent gas clouds, including tidal effects from a distant massive object.

Findings

Collision outcomes depend on energy ratios and collision angles.

Tidal effects influence the collapse dynamics and structure formation.

Different initial conditions lead to varied gravitational collapse pathways.

Abstract

We simulate the collapse of a turbulent gas cloud with the particle-based code Gadget2. We choose two sub-clouds, formed by those particles located around the centers $\vec{r}_L$ and $\vec{r}_R$ and within the radii $r_L$ and $r_R$, respectively. A translational velocity $\vec{v}_L$ or $\vec{v}_R$ is added, so that the sub-clouds move towards each other to collide. The radius and pre-collision velocity of the sub-clouds are chosen to be un-equal, and both head-on and oblique collisions are considered. The simulations are all calibrated to have the same total mass and the initial energy ratio $\alpha=0.16$, which is defined as the ratio of thermal energy to gravitational energy. We compare low-$\beta$ models to a high-$\beta$ models, where $\beta$ is defined as the ratio of kinetic energy to gravitational energy. Finally, we consider the turbulent cloud to be under the gravitational influence of an object located far enough, in order to approximate the tidal effects by means of an azimuthal velocity $V_{\rm cir}$ added to the cloud particles in addition to the translational and turbulent velocities mentioned above. We compare a low-$V_{\rm cir}$ model with a high-$V_{\rm cir}$ one.