HAWC High Energy Upgrade with a Sparse Array

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory has been fully operational since March 2015. To improve its sensitivity at the highest energies, it is being upgraded with an additional sparse array called outrigger array. We will discuss in this contribution, the different outrigger array components, and the simulation results to optimize it.Comment: Proceeding paper of a contribution at the RICAP16 6th Roma International Conference on Astroparticle Physics in Rome, Ital