GW170817 is the only gravitational-wave event for which a confirmed 3-ray counterpart, GRB 170817A, has been detected. Here, we present a method to search for another type of 3-ray signal, a 3-ray burst precursor, associated with a compact binary merger. If emitted shortly before the coalescence, a high-energy electromagnetic (EM) flash travels through a highly dynamical and relativistic environment, created by the two compact objects orbiting each other. Thus, the EM signal arriving at an Earth observer could present a somewhat predictable time-dependent modulation. We describe a targeted search method for light curves exhibiting such a modulation, parameterized by the observer-frame component masses and binary merger time, using Fermi-GBM data. The sensitivity of the method is assessed based on simulated signals added to GBM data. The method is then applied to a selection of potentially interesting compact binary mergers detected during the second (O2) and third (O3) observing runs of Advanced LIGO and Advanced Virgo. We find no significant modulated 3-ray precursor signal associated with any of the considered events.
Bibliographical noteFunding Information:
T.D.C. was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASA, during part of this work. M. W. Coughlin acknowledges support from the National Science Foundation with grant Nos. PHY-2010970 and OAC-2117997.
© 2022. The Author(s). Published by the American Astronomical Society.