Determination of X-ray pulsar geometry with IXPE polarimetry
Abstract
Using observations of X-ray pulsar Her X-1 by the Imaging X-ray Polarimetry Explorer, we report on a highly significant () detection of the polarization signal from an accreting neutron star. The observed degree of the linear polarization of 10\% is found to be far below theoretical expectations for this object, and stays low throughout the spin cycle of the pulsar. Both the polarization degree and the angle exhibit variability with pulse phase, which allowed us to measure the pulsar spin position angle 57(2) deg and the magnetic obliquity 12(4) deg, which is an essential step towards detailed modelling of the intrinsic emission of X-ray pulsars. Combining our results with the optical polarimetric data, we find that the spin axis of the neutron star and the angular momentum of the binary orbit are misaligned by at least 20 deg, which is a strong argument in support of the models explaining stability of the observed super-orbital variability with the precession of the neutron star.
Cite
@article{arxiv.2206.07138,
title = {Determination of X-ray pulsar geometry with IXPE polarimetry},
author = {Victor Doroshenko and Juri Poutanen and Sergey S. Tsygankov and Valery F. Suleimanov and Matteo Bachetti and Ilaria Caiazzo and Enrico Costa and Alessandro Di Marco and Jeremy Heyl and Fabio La Monaca and Fabio Muleri and Alexander A. Mushtukov and George G. Pavlov and Brian D. Ramsey and John Rankin and Andrea Santangelo and Paolo Soffitta and Rüdiger Staubert and Martin C. Weisskopf and Silvia Zane and Iván Agudo and Lucio A. Antonelli and Luca Baldini and Wayne H. Baumgartner and Ronaldo Bellazzini and Stefano Bianchi and Stephen D. Bongiorno and Raffaella Bonino and Alessandro Brez and Niccolò Bucciantini and Fiamma Capitanio and Simone Castellano and Elisabetta Cavazzuti and Stefano Ciprini and Alessandra De Rosa and Ettore Del Monte and Laura Di Gesu and Niccolò Di Lalla and Immacolata Donnarumma and Michal Dovciak and Steven R. Ehlert and Teruaki Enoto and Yuri Evangelista and Sergio Fabiani and Riccardo Ferrazzoli and Javier A. Garcia and Shuichi Gunji and Kiyoshi Hayashida and Wataru Iwakiri and Svetlana G. Jorstad and Vladimir Karas and Takao Kitaguchi and Jeffery J. Kolodziejczak and Henric Krawczynski and Luca Latronico and Ioannis Liodakis and Simone Maldera and Alberto Manfreda and Frédéric Marin and Andrea Marinucci and Alan P. Marscher and Herman L. Marshall and Giorgio Matt and Ikuyuki Mitsuishi and Tsunefumi Mizuno and C. -Y. Ng and Stephen L. O'Dell and Nicola Omodei and Chiara Oppedisano and Alessandro Papitto and Abel L. Peirson and Matteo Perri and Melissa Pesce-Rollins and Maura Pilia and Andrea Possenti and Simonetta Puccetti and Ajay Ratheesh and Roger W. Romani and Carmelo Sgrò and Patrick Slane and Gloria Spandre and Rashid A. Sunyaev and Toru Tamagawa and Fabrizio Tavecchio and Roberto Taverna and Yuzuru Tawara and Allyn F. Tennant and Nicolas E. Thomas and Francesco Tombesi and Alessio Trois and Roberto Turolla and Jacco Vink and Kinwah Wu and Fei Xie},
journal= {arXiv preprint arXiv:2206.07138},
year = {2023}
}
Comments
31 pages 7 figures, published