Polarisation Leakage due to Errors in Track Reconstruction in Gas Pixel Detectors

Abstract

X-ray polarimetry, based on Gas Pixel Detectors (GPDs), have reached a high level of maturity with the Imaging X-ray Polarimeter Explorer (IXPE) leading to the first ever spatially resolved polarimetric measures. However, being this a new technique, a few unexpected effect have emerged during in flight operations. In particular it was almost immediately found that on-board unpolarized calibration sources were showing radially polarized halos. The origin of this features was recognized in a correlation between the error in reconstructing the absorption point of the X-ray photon and the direction of its electric field vector. Here we present and discuss in detail this effect, showing that it is possible to provide a simple and robust mathematical formalism to handle it. We further show its role and relevance for the recent IXPE measures, and for the use of GPD-based techniques in general, and illustrate how to model it in the study of extended sources.

arXiv comment19 pages, 10 figures, to be published in A&A

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Cited by in corpus (8)

• Discovery of a shock-compressed magnetic field in the north-western rim of the young supernova remnant RX J1713.7-3946 with X-ray polarimetry
• Polarization Leakage and the IXPE PSF
• Improved Measurements of the IXPE Crab Polarization
• Joint machine learning and analytic track reconstruction for X-ray polarimetry with gas pixel detectors
• A polarized view of the young Pulsar Wind Nebula 3C 58 with IXPE
• Advanced Weights for IXPE Polarization Analysis
• Mitigating Polarization Leakage in Gas Pixel Detectors through Hybrid Machine Learning and Analytic Event Reconstruction
• Spatially resolved polarization variation of the Crab Nebula