Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1

Weakly magnetized neutron stars in X-ray binaries show a complex phenomenology with several spectral components that can be associated with the accretion disk, the boundary, and/or a spreading layer, a corona, and a wind. Spectroscopic information alone, however, is not enough to distinguish these components. The analysis of the timing data revealed that most of the variability, and in particular, kilohertz quasi-period oscillations, are associated with the high-energy component that corresponds to the boundary and/or spreading layer. Additional information about the nature of the spectral components, and in particular, about the geometry of the emission region, can be provided by X-ray polarimetry. One of the objects of the class, a bright, persistent, and rather peculiar galactic Type I X-ray burster GX 13+1, was observed with the Imaging X-ray Polarimetry Explorer (IXPE) and the XMM–Newton . Using the XMM–Newton data, we obtained the best-fit values for the continuum spectral parameters and detected strong absorption lines associated with the accretion disk wind. IXPE data showed the source to be significantly polarized in the 2–8 keV energy band, with an overall polarization degree (PD) of 1.4%±0.3% at a polarization angle (PA) of −2° ±6° (errors at the 68% confidence level). During the two-day long observation, we detected rotation of the PA by about 70° with the corresponding changes in the PD from 2% to nondetectable and then up to 5%. These variations in polarization properties are not accompanied by visible spectral state changes of the source. The energy-resolved polarimetric analysis showed a significant change in polarization, from being strongly dependent on energy at the beginning of the observation to being almost constant with energy in the later parts of the observation. As a possible interpretation, we suggest a constant polarization component, strong wind scattering, or a different polarization of the two main spectral components with an individually peculiar behavior. The rotation of the PA suggests a misalignment of the neutron star spin from the orbital axis.

Authors

Institutions

Publication Details

Journal
Astronomy and Astrophysics
Published
2024-08-01
DOI
https://doi.org/10.1051/0004-6361/202449318
Citations
22
Primary Topic
Astrophysical Phenomena and Observations
Type
article
Field-Weighted Citation Impact
7.29

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1

Niccolò Di Lalla, Chris Done, Sofia V. Forsblom, Fabian Kislat et al.
22 citations
Astronomy and Astrophysics
Astrophysical Phenomena and Observations
7.29
article

Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1

Niccolò Di Lalla, Chris Done, Sofia V. Forsblom, Fabian Kislat, Tuomo Salmi, F. Massaro, Jeffery J. Kolodziejczak, Juri Poutanen, R. Bonino, A. Brez, Laura Di Gesu, Simonetta Puccetti, Michal Dovčiak, Y. Evangelista, S. Ciprini, Silvia Zane, M. Pilia, Allyn F. Tennant, Daniele Rogantini, Jeremy Heyl, Andrea Possenti, Victor Doroshenko, Chien‐Ting Chen, Jacco Vink, Herman L. Marshall, Anna Bobrikova, Ioannis Liodakis, F. Ursini, E. Costa, F. Tavecchio, G. Matt, Javier A. García, Pierre-Olivier Petrucci, Alessandro Di Marco, P. Soffitta, Alberto Manfreda, W. H. Baumgartner, Alessandra De Rosa, Kinwah Wu, M. Perri, Martin C. Weisskopf, E. Del Monte, J. J. E. Kajava, G. Spandre, O. J. Roberts, Fei Xie, George G. Pavlov, Roger W. Romani, I. Agudo, Francesco Tombesi, M. Pesce-Rollins, Frédéric Marin, Patrick Slane, Toru Tamagawa, Yuzuru Tawara, Fiamma Capitanio, Steven R. Ehlert, Stephen L. O’Dell, Stephen D. Bongiorno, S. Maldera, C. Sgrò, V. Karas, John Rankin, Alessandro Papitto, A. Trois, Sergey S. Tsygankov, Andrea Gnarini, Riccardo Ferrazzoli, W. Iwakiri, Fabio Muleri, Brian D. Ramsey, Tsunefumi Mizuno, Ikuyuki Mitsuishi, Roberto Taverna, Teruaki Enoto, R. Bellazzini, E. Cavazzuti, Sergio Fabiani, Douglas A. Swartz, H. Krawczynski, Shuichi Gunji, Mason Ng, Michela Negro, Andrea Marinucci, Alan P. Marscher, Abel L. Peirson, Matteo Bachetti, C. Oppedisano, Simone Castellano, P. Kaaret, L. Baldini, Ajay Ratheesh, N. Bucciantini, Vladislav Loktev, Fabio La Monaca, L. Latronico, Nicholas E. Thomas, I. Donnarumma, Alexandra Veledina, L. A. Antonelli, S. Bianchi, Anagha P. Nitindala, Swati Ravi, Roberto Turolla, N. Omodei, C.‐Y. Ng, Kiyoshi Hayashida, Takao Kitaguchi, S. G. Jorstad
article en
22 citations

Abstract

Weakly magnetized neutron stars in X-ray binaries show a complex phenomenology with several spectral components that can be associated with the accretion disk, the boundary, and/or a spreading layer, a corona, and a wind. Spectroscopic information alone, however, is not enough to distinguish these components. The analysis of the timing data revealed that most of the variability, and in particular, kilohertz quasi-period oscillations, are associated with the high-energy component that corresponds to the boundary and/or spreading layer. Additional information about the nature of the spectral components, and in particular, about the geometry of the emission region, can be provided by X-ray polarimetry. One of the objects of the class, a bright, persistent, and rather peculiar galactic Type I X-ray burster GX 13+1, was observed with the Imaging X-ray Polarimetry Explorer (IXPE) and the XMM–Newton . Using the XMM–Newton data, we obtained the best-fit values for the continuum spectral parameters and detected strong absorption lines associated with the accretion disk wind. IXPE data showed the source to be significantly polarized in the 2–8 keV energy band, with an overall polarization degree (PD) of 1.4%±0.3% at a polarization angle (PA) of −2° ±6° (errors at the 68% confidence level). During the two-day long observation, we detected rotation of the PA by about 70° with the corresponding changes in the PD from 2% to nondetectable and then up to 5%. These variations in polarization properties are not accompanied by visible spectral state changes of the source. The energy-resolved polarimetric analysis showed a significant change in polarization, from being strongly dependent on energy at the beginning of the observation to being almost constant with energy in the later parts of the observation. As a possible interpretation, we suggest a constant polarization component, strong wind scattering, or a different polarization of the two main spectral components with an individually peculiar behavior. The rotation of the PA suggests a misalignment of the neutron star spin from the orbital axis.

Astronomy and AstrophysicsVol. 688
University of Pisa (IT), Boston University (US), Yamagata University (JP), Hiroshima University (JP), University of Rome Tor Vergata (IT), Roma Tre University (IT), Louisiana State University (US), Marshall Space Flight Center (US), Centre National de la Recherche Scientifique (FR), Goddard Space Flight Center (US), Pennsylvania State University (US), Universities Space Research Association (US), University of Padua (IT), University of British Columbia (CA), Guangxi University (CN), University of Turku (FI), Chiba University (JP), Istituto Nazionale di Fisica Nucleare (IT), University of New Hampshire (US), Stockholm University (SE), Kavli Institute for the Physics and Mathematics of the Universe (JP), St Petersburg University (RU), Durham University (GB), Washington University in St. Louis (US), Arcetri Astrophysical Observatory (IT), Astronomical Observatory of Rome (IT), Czech Academy of Sciences, Astronomical Institute (CZ), Agenzia Spaziale Italiana (IT), Observatoire astronomique de Strasbourg (FR), Brera Astronomical Observatory (IT), European Space Astronomy Centre (ES), Kavli Institute for Particle Astrophysics and Cosmology (US), Istituto Nazionale di Fisica Nucleare, Sezione di Torino (IT), Institute for Space Astrophysics and Planetology (IT), Pioneer (Japan) (JP), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (IT), Institut de Planétologie et d'Astrophysique de Grenoble (FR), RIKEN (JP), Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata (IT), Center for Astrophysics Harvard & Smithsonian (US), Istituto Nazionale di Fisica Nucleare, Sezione di Firenze (IT), Osservatorio Astronomico di Cagliari (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Roma I (IT), Instituto de Astrofísica de Andalucía (ES), Istituto Nazionale di Fisica Nucleare, Sezione di Pisa (IT), University of Florence (IT), University College London (GB), University of Turin (IT), Nagoya University (JP), Massachusetts Institute of Technology (US), University of Maryland, College Park (US), Université de Strasbourg (FR), The University of Tokyo (JP), University of Tübingen (DE), Sapienza University of Rome (IT), KTH Royal Institute of Technology (SE), University of Amsterdam (NL), University of Hong Kong (HK), Université Grenoble Alpes (FR), Stanford University (US), The University of Osaka (JP)
National Aeronautics and Space Administration, Oak Ridge Associated Universities, European Commission, Deutscher Akademischer Austauschdienst, Academy of Finland, Agenzia Spaziale Italiana, Istituto Nazionale di Astrofisica, Ministero degli Affari Esteri e della Cooperazione Internazionale, Istituto Nazionale di Fisica Nucleare, Marshall Space Flight Center, Goddard Space Flight Center, Institut sur la Nutrition et les Aliments Fonctionnels
Affordable and clean energy
Openalex Percentile: Top 2%
Astrophysical Phenomena and Observations
7.29
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.