Connections between the circumgalactic medium (CGM) gas accretion and the galaxy central star formation has long been inspected. In a series of two papers, we put this interlink between the CGM and star formation into a framework on a larger scale (several hundreds of kpcs), i.e., the merging environment of neighbouring galaxies. Such an environment, to a certain degree, maps out various paths for galaxy interactions including mergers and fly-bys. In this series, we use the IllutrisTNG-100 simulation to demonstrate that this environment can modulate the CGM gas angular momentum, resulting in either enhance or prohibit star formation inside the galaxy.
