In Unison Observations and predictions of compact-object merger emission

Compact-object mergers are ideal cosmic laboratories for studying both gravitational and electromagnetic phenomena. This thesis covers different combinations of techniques to explore the emission of these mergers. First, we make predictions for a particularly peculiar effect predicted by general relativity, known as the gravitational wave (GW) memory effect. We forecast that after five years of data collection, the advanced LIGO and Virgo GW detectors are expected to detect the nonlinear GW memory effect with a signal-to-noise ratio of about three. Then, we shift our focus toward finding the radio afterglow of one of the first NS mergers observed in GWs using Apertif on the Westerbork Synthesis Radio Telescope. Despite identifying 25 candidates based on their variability and 55 transient candidates detected in one observation, none can be associated with a host galaxy at the distance of the merger. Next, we utilise recent population synthesis results of black hole - neutron star (BHNS) mergers to give insight into the capabilities of future GW and electromagnetic (EM) observatories. We find that with the next-generation Einstein telescope and the Square Kilometre Array, the probability of localising a short gamma-ray burst (GRB) associated with a BHNS merger and observing the radio afterglow nears unity. Finally, we use deep-learning techniques to massively speed up complicated hydrodynamic simulations of GRB afterglows and to investigate the connection between the prompt and the afterglow phase of GRBs.