A1 Refereed original research article in a scientific journal
X-Ray Polarimetry of the Dipping Accreting Neutron Star 4U 1624–49
Authors: Saade M. Lynne, Kaaret Philip, Gnarini Andrea, Poutanen Juri, Ursini Francesco, Bianchi Stefano, Bobrikova Anna, La Monaca Fabio, Di Marco Alessandro, Capitanio Fiamma, Veledina Alexandra, Agudo Iván, Antonelli Lucio A., Bachetti Matteo, Baldini Luca, Baumgartner Wayne H., Bellazzini Ronaldo, Bongiorno Stephen D., Bonino Raffaella, Brez Alessandro, Bucciantini Niccolò, Castellano Simone, Cavazzuti Elisabetta, Chen Chien-Ting, Ciprini Stefano, Costa Enrico, De Rosa Alessandra, Del Monte Ettore, Di Gesu Laura, Di Lalla Niccolò, Donnarumma Immacolata, Doroshenko Victor, Dovčiak Michal, Ehlert Steven R., Enoto Teruaki, Evangelista Yuri, Fabiani Sergio, Ferrazzoli Riccardo, García Javier A., Gunji Shuichi, Hayashida Kiyoshi, Heyl Jeremy, Iwakiri Wataru, Jorstad Svetlana G., Karas Vladimir, Kislat Fabian, Kitaguchi Takao, Kolodziejczak Jeffery J., Krawczynski Henric, 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 Chi-Yung, O’Dell Stephen L., Omodei Nicola, Oppedisano Chiara, Papitto Alessandro, Pavlov George G., Peirson Abel L., 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, Tsygankov Sergey S., Turolla Roberto, Vink Jacco, Weisskopf Martin C., Wu Kinwah, Xie Fei, Zane Silvia
Publisher: Institute of Physics Publishing
Publication year: 2024
Journal: Astrophysical Journal
Journal name in source: The Astrophysical Journal
Article number: 133
Volume: 963
Issue: 2
eISSN: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ad235a
Web address : https://dx.doi.org/10.3847/1538-4357/ad235a
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/387339076
Preprint address: https://arxiv.org/abs/2312.11655
We present the first X-ray polarimetric study of the dipping accreting neutron star 4U 1624−49 with the Imaging X-ray Polarimetry Explorer. We report a detection of polarization in the nondip time intervals with a confidence level of 99.99%. We find an average polarization degree (PD) of 3.1% ± 0.7% and a polarization angle of 81° ± 6° east of north in the 2–8 keV band. We report an upper limit on the PD of 22% during the X-ray dips with 95% confidence. The PD increases with energy, reaching from 3.0% ± 0.9% in the 4–6 keV band to 6% ± 2% in the 6–8 keV band. This indicates the polarization likely arises from Comptonization. The high PD observed is unlikely to be produced by Comptonization in the boundary layer or spreading layer alone. It can be produced by the addition of an extended geometrically thin slab corona covering part of the accretion disk, as assumed in previous models of dippers, and/or a reflection component from the accretion disk.
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