Title: | Complex rotational dynamics of the neutron star in Hercules X-1 revealed by X-ray polarization |
Authors: | Heyl, Jeremy Doroshenko, Victor González-Caniulef, Denis Caiazzo, Ilaria Poutanen, Juri Mushtukov, Alexander Tsygankov, Sergey S. Kirmizibayrak, Demet BACHETTI, Matteo Pavlov, George G. Forsblom, Sofia V. MALACARIA, Christian Suleimanov, Valery F. Agudo, Iván ANTONELLI, Lucio Angelo Baldini, Luca Baumgartner, Wayne H. Bellazzini, Ronaldo Bianchi, Stefano Bongiorno, Stephen D. Bonino, Raffaella Brez, Alessandro BUCCIANTINI, Niccolo' CAPITANIO, FIAMMA Castellano, Simone Cavazzuti, Elisabetta Chen, Chien-Ting Ciprini, Stefano COSTA, ENRICO DE ROSA, Alessandra DEL MONTE, Ettore Di Gesu, Laura Di Lalla, Niccolò DI MARCO, Alessandro Donnarumma, Immacolata Dovčiak, Michal Ehlert, Steven R. Enoto, Teruaki EVANGELISTA, YURI FABIANI, Sergio FERRAZZOLI, Riccardo Garcia, Javier A. Gunji, Shuichi Hayashida, Kiyoshi Iwakiri, Wataru Jorstad, Svetlana G. Kaaret, Philip Karas, Vladimir Kislat, Fabian Kitaguchi, Takao Kolodziejczak, Jeffery J. Krawczynski, Henric LA MONACA, Fabio Latronico, Luca Liodakis, Ioannis Maldera, Simone Manfreda, Alberto Marin, Frédéric Marinucci, Andrea Marscher, Alan P. Marshall, Herman L. MASSARO, FRANCESCO Matt, Giorgio Mitsuishi, Ikuyuki Mizuno, Tsunefumi MULERI, FABIO Negro, Michela Ng, C. -Y. O'Dell, Stephen L. Omodei, Nicola Oppedisano, Chiara PAPITTO, ALESSANDRO Peirson, Abel Lawrence PERRI, Matteo Pesce-Rollins, Melissa Petrucci, Pierre-Olivier PILIA, Maura POSSENTI, ANDREA Puccetti, Simonetta Ramsey, Brian D. RANKIN, John RATHEESH, AJAY Roberts, Oliver J. Romani, Roger W. Sgrò, Carmelo Slane, Patrick SOFFITTA, PAOLO Spandre, Gloria Swartz, Douglas A. Tamagawa, Toru TAVECCHIO, Fabrizio Taverna, Roberto Tawara, Yuzuru Tennant, Allyn F. Thomas, Nicholas E. TOMBESI, Francesco TROIS, ALESSIO Turolla, Roberto Vink, Jacco Weisskopf, Martin C. Wu, Kinwah XIE, FEI Zane, Silvia |
Issue Date: | 2024 |
Journal: | NATURE ASTRONOMY |
Number: | 8 |
Issue: | 8 |
First Page: | 1047 |
Abstract: | In an accreting X-ray pulsar, a neutron star accretes matter from a companion star through an accretion disk. The magnetic field of the rotating neutron star disrupts the inner edge of the disk, funnelling the gas to flow onto the poles on its surface. Hercules X-1 is a prototypical persistent X-ray pulsar about 7 kpc from Earth. Its emission varies on three distinct timescales: the neutron star rotates every 1.2 s, it is eclipsed by its companion each 1.7 d, and the system exhibits a superorbital period of 35 d, which has remained stable since its discovery. Several lines of evidence point to the source of this variation as the precession of the accretion disk or that of the neutron star. Despite the many hints over the past 50 yr, the precession of the neutron star itself has yet not been confirmed or refuted. X-ray polarization measurements (probing the spin geometry of Her X-1) with the Imaging X-ray Polarimetry Explorer suggest that free precession of the neutron star crust sets the 35 d period; this has the important implication that its crust is somewhat asymmetric by a few parts per ten million. |
URI: | http://hdl.handle.net/20.500.12386/35667 |
URL: | https://api.elsevier.com/content/abstract/scopus_id/85196307045 https://www.nature.com/articles/s41550-024-02295-8 |
ISSN: | 2397-3366 |
DOI: | 10.1038/s41550-024-02295-8 |
Bibcode ADS: | 2024NatAs...8.1047H |
Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista
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