The Imaging X-ray Polarimetry Explorer (IXPE) observed for the first time highly polarized X-ray emission from the magnetar 1E 1841-045, targeted after a burst-active phase in August 2024. To date, IXPE has observed four other magnetars during quiescent periods, highlighting substantially different polarization properties. 1E 1841-045 exhibits a high, energy-dependent polarization degree, which increases monotonically from ~15% at 2-3 keV up to ~55% at 5.5-8 keV, while the polarization angle, aligned with the celestial North, remains fairly constant. The broadband spectrum (2-79 keV) obtained by combining simultaneous IXPE and NuSTAR data is well modeled by a blackbody and two power-law components. The unabsorbed 2-8 keV flux (~2E-11 erg/cm2/s) is about 10% higher than that obtained from archival XMM-Newton and NuSTAR observations. The polarization of the soft, thermal component does not exceed ~25%, and may be produced by a condensed surface or a bombarded atmosphere. The intermediate power law is polarized at around 30%, consistent with predictions for resonant Compton scattering in the star magnetosphere; while, the hard power law exhibits a polarization degree exceeding 65%, pointing to a synchrotron/curvature origin.
@article{arxiv.2412.15811,
title = {IXPE detection of highly polarized X-rays from the magnetar 1E 1841-045},
author = {Michela Rigoselli and Roberto Taverna and Sandro Mereghetti and Roberto Turolla and Gian Luca Israel and Silvia Zane and Lorenzo Marra and Fabio Muleri and Alice Borghese and Francesco Coti Zelati and Davide De Grandis and Matteo Imbrogno and Ruth M. E. Kelly and Paolo Esposito and Nanda Rea},
journal= {arXiv preprint arXiv:2412.15811},
year = {2025}
}
Comments
Accepted for publication in ApJL together with a companion paper by Stewart et al. Comments are welcome