A polarimetrically oriented X-ray stare at the accreting pulsar EXO 2030+375
Abstract
Accreting X-ray pulsars (XRPs) are presumably ideal targets for polarization measurements, as their high magnetic field strength is expected to polarize the emission up to a polarization degree of ~80%. However, such expectations are being challenged by recent observations of XRPs with the Imaging X-ray Polarimeter Explorer (IXPE). Here we report on the results of yet another XRP, EXO 2030+375, observed with IXPE and contemporarily monitored with Insight-HXMT and SRG/ART-XC. In line with recent results obtained with IXPE for similar sources, analysis of the EXO 2030+375 data returns a low polarization degree of 0%-3% in the phase-averaged study and variation in the range 2%-7% in the phase-resolved study. Using the rotating vector model we constrain the geometry of the system and obtain a value for the magnetic obliquity of ~. Considering also the estimated pulsar inclination of ~, this indicates that the magnetic axis swings close to the observer line of sight. Our joint polarimetric, spectral and timing analysis hint to a complex accreting geometry where magnetic multipoles with asymmetric topology and gravitational light bending significantly affect the observed source behavior.
Keywords
Cite
@article{arxiv.2304.00925,
title = {A polarimetrically oriented X-ray stare at the accreting pulsar EXO 2030+375},
author = {Christian Malacaria and Jeremy Heyl and Victor Doroshenko and Sergey S. Tsygankov and Juri Poutanen and Sofia V. Forsblom and Fiamma Capitanio and Alessandro Di Marco and Yujia Du and Lorenzo Ducci and Fabio La Monaca and Alexander A. Lutovinov and Herman L. Marshall and Ilya A. Mereminskiy and Sergey V. Molkov and Mason Ng and Pierre-Olivier Petrucci and Andrea Santangelo and Andrey E. Shtykovsky and Valery F. Suleimanov and Ivan Agudo and Lucio A. Antonelli and Matteo Bachetti and Luca Baldini and Wayne H. Baumgartner and Ronaldo Bellazzini and Stefano Bianchi and Stephen D. Bongiorno and Raffaella Bonino and Alessandro Brez and Niccolo Bucciantini and Simone Castellano and Elisabetta Cavazzuti and Chien-Ting Chen and Stefano Ciprini and Enrico Costa and Alessandra De Rosa and Ettore Del Monte and Laura Di Gesu and Niccolo 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 Philip Kaaret and Vladimir Karas and Fabian Kislat and Takao Kitaguchi and Jeffery J. Kolodziejczak1 and Henric Krawczynski and Luca Latronico and Ioannis Liodakis and Simone Maldera and Alberto Manfreda and Frederic Marin and Andrea Marinucci and Alan P. Marscher and Francesco Massaro and Giorgio Matt and Ikuyuki Mitsuishi and Tsunefumi Mizuno and Fabio Muleri and Michela Negro and Chi-Yung Ng and Stephen L. O'Dell and Nicola Omodei and Chiara Oppedisano and Alessandro Papitto and George G. Pavlov and Abel L. Peirson and Matteo Perri and Melissa Pesce-Rollins and Maura Pilia and Andrea Possenti and Simonetta Puccetti and Brian D. Ramsey and John Rankin and Ajay Ratheesh and Oliver J. Roberts and Roger W. Romani and Carmelo Sgro and Patrick Slane and Paolo Soffitta and Gloria Spandre and Douglas A. Swartz and Toru Tamagawa and Fabrizio Tavecchio and Roberto Taverna and Yuzuru Tawara and Allyn F. Tennant and Nicholas E. Thomas and Francesco Tombesi and Alessio Trois and Roberto Turolla and Jacco Vink and Martin C. Weisskopf and Kinwah Wu and Fei Xie and Silvia Zane},
journal= {arXiv preprint arXiv:2304.00925},
year = {2023}
}
Comments
A&A accepted. Proofs version