The role of collision speed, cloud density, and turbulence in the formation of young massive clusters via cloud-cloud collisions

TL;DR

This study uses hydrodynamical simulations to investigate how collision speed, cloud density, and turbulence influence the formation of young massive clusters from giant molecular cloud collisions, revealing key conditions for their formation.

Contribution

It provides new insights into the specific physical parameters that lead to the formation of young massive clusters through cloud-cloud collisions, supported by detailed simulations.

Findings

Higher collision speeds increase star formation rates.

Greater initial cloud density results in more massive clusters.

Lower turbulence levels favor the formation of Milky Way-like YMCs.

Abstract

Young massive clusters (YMCs) are recently formed astronomical objects with unusually high star formation rates. We propose the collision of giant molecular clouds (GMCs) as a likely formation mechanism of YMCs, consistent with the YMC conveyor-belt formation mode concluded by other authors. We conducted smoothed particle hydrodynamical simulations of cloud-cloud collisions and explored the effect of the clouds' collision speed, initial cloud density, and the level of cloud turbulence on the global star formation rate and the properties of the clusters formed from the collision. We show that greater collision speed, greater initial cloud density and lower turbulence increase the overall star formation rate and produce clusters with greater cluster mass. In general, collisions with relative velocity $\gtrsim 25$ km/s, initial cloud density $\gtrsim 250$ cm$^{-3}$, and turbulence of $\approx 2.5$ km/s can produce massive clusters with properties resembling the observed Milky Way YMCs.