A Generalized Framework for Rapid Polarization Response Generation in Wide Field-of-View Compton Polarimeters
Abstract
Polarimetry is the most direct probe of the unsettled radiation mechanism and magnetic field structure of gamma-ray burst (GRB) prompt emission at the energies where it peaks, tens of keV to about 1 MeV. Compton polarimeters use the azimuthal scattering angle distribution (ASAD), a 180 degree modulation on axis. GRB measurements have largely relied on the on-axis modulation factor μ100. For a wide field-of-view planar polarimeter, GRBs arrive off axis, where the Klein-Nishina projection adds harmonics to the ASAD. Muleri (2014) described this projection and evaluated it in a low-energy expansion for X-rays. We evaluate it numerically without approximation over the whole prompt-emission energy band for any incidence and polarization angles, quantify the off-axis harmonics a single modulation factor cannot capture, and verify the model against GEANT4 simulations of an ideal polarimeter. We also include the effect of the detection threshold on the ASAD. With POLAR as the case study, we present two modes that build the full polarization response with at least 95 percent fewer Monte Carlo simulations. Mode 1 takes only the unpolarized simulation per energy and recovers the polarization measured with POLAR's full GEANT4 responses for all but the brightest GRBs, where it underestimates the polarization degree. Mode 2 adds two polarized simulations per energy at distinct angles and reproduces the simulated ASADs to their statistical noise and the polarization of every GRB tested. Both modes are released as open-source software for any planar Compton polarimeter.
Versions
Related
- Probing Scalar Polarization with Next-Generation Gravitational-Wave Detectors: The Roles of Detector Geometry and Source Inclination
- In search of the third dimension in Compton X-ray polarimeters
- Deconvolved IXPE Polarization Maps of the Crab Nebula in a Maximum-a-Posteriori Framework
- A Framework for Automated Multi-Source Satellite Data Analytics and LLM-Based Report Generation
- ASTRA: An Autonomous Framework for Physics-Validated Analysis and Hypothesis Generation in Astrophysics
BibTeX
@misc{zaid2026generalized,
title = {{A Generalized Framework for Rapid Polarization Response Generation in Wide Field-of-View Compton Polarimeters}},
author = {Mohamed Gamal Zaid and Merlin Kole and Mark McConnell and Fabio Muleri and Hancheng Li},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31559},
eprint = {2610.31559},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31559},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Generalized Framework for Rapid Polarization Response Generation in Wide Field-of-View Compton Polarimeters
AU - Mohamed Gamal Zaid
AU - Merlin Kole
AU - Mark McConnell
AU - Fabio Muleri
AU - Hancheng Li
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31559
UR - https://arxiv.org/abs/2610.31559
AB - Polarimetry is the most direct probe of the unsettled radiation mechanism and magnetic field structure of gamma-ray burst (GRB) prompt emission at the energies where it peaks, tens of keV to about 1 MeV. Compton polarimeters use the azimuthal scattering angle distribution (ASAD), a 180 degree modulation on axis. GRB measurements have largely relied on the on-axis modulation factor μ_100. For a wide field-of-view planar polarimeter, GRBs arrive off axis, where the Klein-Nishina projection adds harmonics to the ASAD. Muleri (2014) described this projection and evaluated it in a low-energy expansion for X-rays. We evaluate it numerically without approximation over the whole prompt-emission energy band for any incidence and polarization angles, quantify the off-axis harmonics a single modulation factor cannot capture, and verify the model against GEANT4 simulations of an ideal polarimeter. We also include the effect of the detection threshold on the ASAD. With POLAR as the case study, we present two modes that build the full polarization response with at least 95 percent fewer Monte Carlo simulations. Mode 1 takes only the unpolarized simulation per energy and recovers the polarization measured with POLAR's full GEANT4 responses for all but the brightest GRBs, where it underestimates the polarization degree. Mode 2 adds two polarized simulations per energy at distinct angles and reproduces the simulated ASADs to their statistical noise and the polarization of every GRB tested. Both modes are released as open-source software for any planar Compton polarimeter.
ER -