The X-ray polarimetry view of the accreting pulsar Cen X-3
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Date
2022-12-01
Authors
Tsygankov, Sergey S.
Doroshenko, Victor
Poutanen, Juri
Heyl, Jeremy
Mushtukov, Alexander A.
Caiazzo, Ilaria
Marco, Alessandro Di
Forsblom, Sofia V.
González-Caniulef, Denis
Klawin, Moritz
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OA Version
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Citation
S.S. Tsygankov, V. Doroshenko, J. Poutanen, J. Heyl, A.A. Mushtukov, I. Caiazzo, A.D. Marco, S.V. Forsblom, D. González-Caniulef, M. Klawin, F.L. Monaca, C. Malacaria, H.L. Marshall, F. Muleri, M. Ng, V.F. Suleimanov, R.A. Sunyaev, R. Turolla, I. Agudo, L.A. Antonelli, M. Bachetti, L. Baldini, W.H. Baumgartner, R. Bellazzini, S. Bianchi, S.D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, E. Costa, A.D. Rosa, E.D. Monte, L.D. Gesu, N.D. Lalla, I. Donnarumma, M. Dovčiak, S.R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J.A. Garcia, S. Gunji, K. Hayashida, W. Iwakiri, S.G. Jorstad, V. Karas, T. Kitaguchi, J.J. Kolodziejczak, H. Krawczynski, L. Latronico, I. Liodakis, S. Maldera, A. Manfreda, F. Marin, A. Marinucci, A.P. Marscher, G. Matt, I. Mitsuishi, T. Mizuno, C.-Y. Ng, S.L. O'Dell, N. Omodei, C. Oppedisano, A. Papitto, G.G. Pavlov, A.L. Peirson, M. Perri, M. Pesce-Rollins, P.-O. Petrucci, M. Pilia, A. Possenti, S. Puccetti, B.D. Ramsey, J. Rankin, A. Ratheesh, R.W. Romani, C. Sgrò, P. Slane, P. Soffitta, G. Spandre, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A.F. Tennant, N.E. Thomas, F. Tombesi, A. Trois, J. Vink, M.C. Weisskopf, K. Wu, F. Xie, S. Zane. 2022. "The X-ray polarimetry view of the accreting pulsar Cen X-3" Letters of the Astrophysical Journal, Volume 941, Issue 1, pp.L14-L14. https://doi.org/10.3847/2041-8213/aca486
Abstract
Cen X-3 is the first X-ray pulsar discovered 50 years ago. Radiation from
such objects is expected to be highly polarized due to birefringence of plasma and vacuum associated with propagation of photons in presence of the strong magnetic field. Here we present results of the observations of Cen X-3 performed with the Imaging X-ray Polarimetry Explorer. The source exhibited significant flux variability and was observed in two states different by a factor of ~20 in flux. In the low-luminosity state no significant polarization was found either in pulse phase-averaged (with the 3𝜎 upper limit of 12%) or phase-resolved data (the 3𝜎 upper limits are 20-30%). In the bright state the polarization degree of 5.8％ ± 0.3% and polarization angle of $49.°6 ±1.°5 with significance of about 20σ was measured from the spectro-polarimetric analysis of the phase-averaged data. The phase-resolved analysis showed a significant anti-correlation between the flux and the polarization degree as well as strong variations of the polarization angle. The fit with the rotating vector model indicates a position angle of the pulsar spin axis of about 49° and a magnetic obliquity of 17°. The detected relatively low polarization can be explained if the upper layers of the neutron star surface are overheated by the accreted matter and the conversion of the polarization modes occurs within the transition region between the upper hot layer and a cooler underlying atmosphere. A fraction of polarization signal can also be produced by reflection of radiation from the neutron star surface and the accretion curtain.
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© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.