Mark Pearce: Hard X-ray polarimetry of the Crab with XL-Calibur

Thursday 22 May 2025, 13:15 → 14:15 Europe/Stockholm

A5:1003

In summer 2024, the linear polarisation of hard X-ray emission from the Crab pulsar and wind nebula was measured by XL-Calibur. Observations were made during a week-long stratospheric balloon flight between Sweden and Canada. The addition of polarimetry to the standard high-energy measurement techniques of spectroscopy, timing and imaging, allows systematically new tests of source emission models. XL-Calibur is the most sensitive hard X-ray polarimetry mission to date, offering an order-of-magnitude improvement in signal-to-background performance compared to preceding missions. The energy range (15-80 keV) complements the NASA/ASI IXPE mission (2-8 keV), allowing broadband studies. I will introduce the XL-Calibur mission, explain how the linear polarisation of hard X-rays is measured, and summarise results from Crab observations. Plans for further hard X-ray polarimetry missions will be briefly described.