The halo merger rate in the Millennium Simulation and implications for observed galaxy merger fractions

Understand

We developed a new method to extract halo merger rates from the Millennium Simulation.

• First, by removing superfluous mergers that are artifacts of the FOF halo finder, we find a lower merger rate compared to previous work.
• The reductions are more significant at lower redshifts, lower halo masses, and minor mergers.
• Our approach agrees better with predictions from the EPS model.