The Convergence Event (or Convergence) is the final process of a Marker and the affected lifeforms of a given planet or planets.
Throughout the series, "convergence" as described by Unitologists was a vague description of becoming a singular entity or made whole by the Marker. Unitologists sought to preserve the bodies of the deceased in mausoleums or, during a Necromorph outbreak, suicide by apparent suffocation or smothering, allowing the lifeform to take over their bodies.
In reality, a convergence event is a process triggered by a marker, when a large enough amount of organic matter has become infected with the necromorph pathogen. At this time the marker will pull all the infected tissue into the stratosphere, where it will form a brethren moon and absorb the marker that created it.
These moons are the source of the signal the Markers transmit, using these signals to draw organic tissue to it or to aid in its construction. The convergence event can be triggered by a large concentration of Necromorphs. The presence of a Marker architect near the Marker they built, as was the case with Isaac Clarke on Titan Station or the Aliens on Tau Volantis, also appears to be a requirement.
The convergence event can be stopped either by the destruction of the Marker that triggered it or by the destruction of the incomplete "Brethren" moon itself. In the case of the moon above Tau Volantis, an alien machine powered by a Codex destroys the moon and its signal.