The LEAP Gamma-Ray Burst Polarimeter: An Overview

The LargE Area Polarimeter, or LEAP, is a proposed mission concept that will radically improve our understanding of some of the most energetic phenomena in our Universe by exposing the underlying physics governing astrophysical jets and the extreme environment surrounding newborn compact objects. LEAP will do this by making the most sensitive polarization measurements to date of the prompt gamma-ray emission from a large sample of Gamma-Ray Bursts (GRBs). The LEAP science objectives are met with a single, proven instrument—a wide Field-of-View (FOV) Compton polarimeter that measures GRB polarization over the energy range from 50–500 keV and simultaneously performs spectroscopy from 20 keV to 5 MeV. Mounted as an external payload on the International Space Station (ISS), LEAP’s large FOV of ±75° (1.5π sr) allows it to continuously monitor the sky for GRBs, ensuring that a significant number of GRBs are observed over the 3-year mission lifetime. The large FOV combined with LEAP’s intrinsic ability to provide source localization and the ISS’s ability for swift downlink permits rapid follow-up by the community, which is essential to providing important context information (counterpart identifications, redshift, afterglow studies, etc.) and to maximizing the science output for the mission. An overview of LEAP’s science objectives and mission design will be presented.