  OLIMPO is a proposed Antarctic balloon-borne Sunyaev-Zel'dovich effect (SZE)
imager to study gas dynamics associated with structure formation along with the
properties of the warm-hot intergalactic medium (WHIM) residing in the
connective filaments. During a 25 day flight OLIMPO will image a total of 10
z~0.05 galaxy clusters and 8 bridges at 145, 250, 365, and 460 GHz at an
angular resolution of 1.0'-3.3'. The maps will be significantly deeper than
those planned from CMB-S4 and CCAT-P, and will have excellent fidelity to the
large angular scales of our low-z targets, which are difficult to probe from
the ground. In combination with X-ray data from eROSITA and XRISM we will
transform our current static view of galaxy clusters into a full dynamic
picture by measuring the internal intra-cluster medium (ICM) velocity structure
with the kinematic SZE, X-ray spectroscopy, and the power spectrum of ICM
fluctuations. Radio observations from ASKAP and MeerKAT will be used to better
understand the connection between ICM turbulence and shocks with the
relativistic plasma. Beyond the cluster boundary, we will combine thermal SZE
maps from OLIMPO with X-ray imaging from eROSITA to measure the thermodynamics
of the WHIM residing in filaments, providing a better understanding of its
properties and its contribution to the total baryon budget.
