Speaker
Description
We present a systematic and quantitative assessment of the Southern Wide-field Gamma-ray Observatory's (SWGO) detection rates for very-high-energy (VHE; >100 GeV) transient sources. Using the SWGO instrument response functions — including effective area, background rates, and point-spread function across three zenith-angle bands and three core-distance bands — we construct spectral templates based on observed or model-derived spectra representative of each source class, rescaled according to luminosity and distance. Our analysis considers four transient populations constrained by observational data: magnetar giant and intermediate flares (modeled using the GRB 200415A template), gamma-ray novae (based on the RS Ophiuchi/LST-1 hadronic model), jetted tidal disruption events, and binary neutron star merger afterglows described by a structured jet model calibrated to GW170817. For each case, the spectral templates are convolved with the SWGO instrument response and evaluated using the Li & Ma significance statistic summed over analysis bins. The resulting sensitivities are then folded with the corresponding astrophysical populations — including luminosity functions, Galactic spatial distributions, and known-source catalogs — to estimate annual detection rates. The analysis pipeline is cross-validated against published gamma-ray burst (GRB) detection rates from Huang et al. (2026) and the non-detection of GW170817 by H.E.S.S. We find that SWGO is expected to detect approximately 0.9–2.5 VHE transient events per year, with the dominant contributions arising from magnetar intermediate flares and active galactic nucleus (AGN) flares, comparable to the predicted GRB detection rate of ~0.5 events per year. We identify three distinct observational regimes governing SWGO transient detectability: rate-limited (GRBs and AGN flares), field-of-view-limited (magnetars), and background-limited (novae and binary neutron star mergers). These results provide the first quantitative characterization of SWGO's transient science capabilities beyond gamma-ray bursts.