IXPE Detects Unprecedented Polarization from Magnetar, Supporting Century-Old Theory

A coordinated campaign using NASA’s Imaging X-ray Polarimetry Explorer, the NICER instrument, and Australia’s Parkes radio telescope observed magnetar 1E 1547-5408 for more than 140 hours between March and April 2025. The star, which rotates every two seconds and emits strong radio and X-ray bursts, displayed X-ray polarization levels nearly threefold higher than those seen in comparable objects. Standard surface-emission models cannot account for such values, leading scientists to invoke vacuum birefringence—a prediction from quantum electrodynamics dating back to 1936 that extreme magnetic fields polarize the vacuum itself.

Co-lead author Hoa Dinh Thi of Rice University and lead author Rachael Stewart of George Washington University say their models require this effect to match both X-ray and radio constraints. The findings, published in Nature, represent the most compelling observational support for the theory to date. Ongoing IXPE observations aim to confirm the result across additional magnetars and explore further exotic quantum phenomena.