Speaker
Description
The Einstein Telescope (ET) will revolutionize gravitational-wave (GW) multi-messenger (MM) science by detecting hundreds of thousands of neutron star (NS) mergers beyond the Local Universe. In the ET era, the bottleneck of GW-MM science will shift from GW detection to the identification of the electromagnetic (EM) counterparts. The main challenges will arise from their faintness and rapid evolution, as well as from the large GW localization volumes, within which vast numbers of galaxies and photometric candidates will need to be inspected. Current follow-up strategies will be pushed to their limits and will no longer be sustainable with existing facilities.
In this context, the Wide-field Spectroscopic Telescope (WST) could be a game changer, enabling deep spectroscopic observations over large fields of view and delivering thousands of spectra simultaneously. I will present the latest results from simulations I carried out within Division 4 of the ET Observational Science Board (OSB) and the Time Domain Working Group of the WST science team, assessing the impact of integral field and multi-object spectroscopy on the detection and identification of EM counterparts of ET NS mergers [Bisero et al. 2026]. I will outline observing strategies with WST, discuss the importance of rapid response to external alerts, and explore selection criteria for GW triggers. I will highlight how ET can drive the design and requirements of next-generation facilities such as WST.