Gravitational-Wave informed pointing of short-gamma-ray bursts observations

The dawn of multimessenger astrophysics (MMA), marked by the joint detection of gravitational waves (GWs) and gamma-rays from a binary neutron star (BNS) merger, has initiated a transformative era in astrophysical research. Next-generation (XG) GW observatories, such as the U.S.-led Cosmic Explorer, are expected to detect BNS mergers nearly once per minute out to redshifts of ~2 and beyond. However, current and planned gamma-ray observatories, including Swift, may face challenges in rapidly following up these events due to communication and repositioning delays, especially as event rates increase. This study develops a probabilistic framework to estimate the orientation and sky location of BNS systems using only the early-warning portion of GW signals, accounting for modeling uncertainties in EM–GW emission. Gamma-ray detectability is highly sensitive to alignment within ≲15° of the observer's line of sight. We simulate ~1,000 BNS mergers–roughly equivalent to one day of observations by an XG GW network–to evaluate early-warning strategies. Preliminary results indicate that the framework can effectively rule out binaries unlikely to produce observable gamma-rays, while constraining a small fraction of systems that are promising candidates for joint detection by Cosmic Explorer and Swift.