Submitted to the Proceedings of the US Community Study on the Future of Particle Physics ( Snowmass 2021 ) Snowmass 2021 Cosmic Frontier White Paper : Ultraheavy particle dark matter

Daniel Carney,1, ∗ Nirmal Raj,2, † Yang Bai,3 Joshua Berger,4 Carlos Blanco,5, 6 Joseph Bramante,7, 8 Christopher Cappiello,7 Máıra Dutra,9 Reza Ebadi,10, 11 Kristi Engel,10 Edward Kolb,12 J. Patrick Harding,13 Jason Kumar,14 Gordan Krnjaic,15, 16 Rafael F. Lang,17 Rebecca K. Leane,18, 19 Benjamin V. Lehmann,20, 21 Shengchao Li,17 Andrew J. Long,22 Gopolang Mohlabeng,7, 8 Ibles Olcina,1, 23 Elisa Pueschel,24 Nicholas L. Rodd,25 Carsten Rott,26, 27 Dipan Sengupta,28, 29 Bibhushan Shakya,30 Ronald L. Walsworth,10, 11 and Shawn Westerdale31 Physics Division, Lawrence Berkeley National Lab, Berkeley, CA, USA TRIUMF, Vancouver, BC Canada Department of Physics, University of Wisconsin-Madison, Madison, WI, USA Department of Physics, Colorado State University, Fort Collins, CO, USA Department of Physics, Princeton University, Princeton, NJ, USA The Oskar Klein Centre, Stockholm University, AlbaNova, Stockholm, Sweden The Arthur B. McDonald Canadian Astroparticle Physics Research Institute and Department of Physics,