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.

19 pages, 10 figures, to be published in A&A

References in corpus (5)

• Magnetars: Properties, Origin and Evolution
• PolarLight: a CubeSat X-ray Polarimeter based on the Gas Pixel Detector
• The imaging properties of the Gas Pixel Detector as a focal plane polarimeter
• Calibration errors in interferometric radio polarimetry
• Towards Optimal Signal Extraction for Imaging X-ray Polarimetry

Cited by in corpus (4)

• 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
• Joint machine learning and analytic track reconstruction for X-ray polarimetry with gas pixel detectors
• Mitigating Polarization Leakage in Gas Pixel Detectors through Hybrid Machine Learning and Analytic Event Reconstruction
• Spatially resolved polarization variation of the Crab Nebula