Search for UHE neutrinos from GRBs with the Pierre Auger Observatory

We report on the search for ultra-high-energy neutrinos from the prompt emission of gamma-ray bursts (GRBs) using Surface Detector (SD) data from Phase I of the Pierre Auger Observatory (2004–2021). A total of 570 GRBs occur within the most neutrino-sensitive field of view of the SD, considering both Earth-skimming and downward-going detection channels. For this purpose, GRB neutrino emission has been modeled using the numerical software NeuCosmA, incorporating gamma-ray measurements and inferred parameters such as the jet Lorentz factor and the minimum variability time scale. No neutrino candidates were found, and upper limits were obtained by stacking the individual GRB neutrino fluences. These limits are complementary to those of IceCube and ANTARES and provide the strongest constraints on prompt GRB neutrino fluence above 10$^{18}$ eV. Additionally, limits on GRB fluence in alternative models of neutrino production have been derived using Auger data.