Refereed journal article or data article (A1)
Determination of X-ray pulsar geometry with IXPE polarimetry
List of Authors: Doroshenko Victor, Poutanen Juri, Tsygankov Sergey S., Suleimanov Valery F., Bachetti Matteo, Caiazzo Ilaria, Costa Enrico, Di Marco Alessandro, Heyl Jeremy, La Monaca Fabio, Muleri Fabio, Mushtukov Alexander A., Pavlov George G., Ramsey Brian D., Rankin John, Santangelo Andrea, Soffitta Paolo, Staubert Rudiger, Weisskopf Martin C., Zane Silvia, Agudo Ivan, Antonelli Lucio A., Baldini Luca, Baumgartner Wayne H., Bellazzini Ronaldo, Bianchi Stefano, Bongiorno Stephen D., Bonino Raffaella, Brez Alessandro, Bucciantini Niccolo, Capitanio Fiamma, Castellano Simone, Cavazzuti Elisabetta, Ciprini Stefano, De Rosa Alessandra, Del Monte Ettore, Di Gesu Laura, Di Lalla Niccolo, Donnarumma Immacolata, Dovciak Michal, Ehlert Steven R., Enoto Teruaki, Evangelista Yuri, Fabiani Sergio, Ferrazzoli Riccardo, Garcia Javier A., Gunji Shuichi, Hayashida Kiyoshi, Iwakiri Wataru, Jorstad Svetlana G., Karas Vladimir, Kitaguchi Takao, Kolodziejczak Jeffery J., Krawczynski Henric, Latronico Luca, Liodakis Ioannis, Maldera Simone, Manfreda Alberto, Marin Frederic, Marinucci Andrea, Marscher Alan P., Marshall Herman L., Matt Giorgio, Mitsuishi Ikuyuki, Mizuno Tsunefumi, Ng Chi-Yung, O'Dell Stephen L., Omodei Nicola, Oppedisano Chiara, Papitto Alessandro, Peirson Abel L., Perri Matteo, Pesce-Rollins Melissa, Pilia Maura, Possenti Andrea, Puccetti Simonetta, Ratheesh Ajay, Romani Roger W., Sgro Carmelo, Slane Patrick, Spandre Gloria, Sunyaev Rashid A., Tamagawa Toru, Tavecchio Fabrizio, Taverna Roberto, Tawara Yuzuru, Tennant Allyn F., Thomas Nicolas E., Tombesi Francesco, Trois Alessio, Turolla Roberto, Vink Jacco, Wu Kinwah, Xie Fei
Publisher: NATURE PORTFOLIO
Publication year: 2022
Journal: Nature Astronomy
Journal name in source: NATURE ASTRONOMY
Journal acronym: NAT ASTRON
Volume number: 6
Start page: 1433
End page: 1443
Number of pages: 13
ISSN: 2397-3366
eISSN: 2397-3366
DOI: http://dx.doi.org/10.1038/s41550-022-01799-5
URL: https://doi.org/10.1038/s41550-022-01799-5
Using observations of X-ray pulsar Hercules X-1 by the Imaging X-ray Polarimetry Explorer we report a highly significant (>17σ) detection of the polarization signal from an accreting neutron star. The observed degree of linear polarization of similar to 10% is far below theoretical expectations for this object, and stays low throughout the spin cycle of the pulsar. Both the degree and angle of polarization exhibit variability with the pulse phase, allowing 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 similar to 20 deg, which is a strong argument in support of the models explaining the stability of the observed superorbital variability with the precession of the neutron star.
