X-ray polarimetry is a unique way to probe the geometrical configuration of highly magnetized accreting neutron stars (X-ray pulsars). GRO J1008-57 is the first transient X-ray pulsar observed at two different flux levels by the Imaging X-ray Polarimetry Explorer (IXPE) during its outburst in November 2022. We find the polarization properties of GRO J1008-57 to be independent of its luminosity, with the polarization degree varying between nondetection and about 15% over the pulse phase. Fitting the phase-resolved spectro-polarimetric data with the rotating vector model allowed us to estimate the pulsar inclination (130 & DEG;, which is in good agreement with the orbital inclination), the position angle (75 & DEG;) of the pulsar spin axis, and the magnetic obliquity (& SIM;74 & DEG;). This makes GRO J1008-57 the first confidently identified nearly orthogonal rotator among X-ray pulsars. We discuss our results in the context of the neutron star atmosphere models and theories of the axis alignment of accreting pulsars.

Tsygankov, S., Doroshenko, V., Mushtukov, A., Poutanen, J., Di Marco, A., Heyl, J., et al. (2023). X-ray pulsar GRO J1008-57 as an orthogonal rotator. ASTRONOMY & ASTROPHYSICS, 675 [10.1051/0004-6361/202346134].

X-ray pulsar GRO J1008-57 as an orthogonal rotator

La Monaca, F;Fabiani, S;Rankin, J;Tombesi, F;
2023-01-01

Abstract

X-ray polarimetry is a unique way to probe the geometrical configuration of highly magnetized accreting neutron stars (X-ray pulsars). GRO J1008-57 is the first transient X-ray pulsar observed at two different flux levels by the Imaging X-ray Polarimetry Explorer (IXPE) during its outburst in November 2022. We find the polarization properties of GRO J1008-57 to be independent of its luminosity, with the polarization degree varying between nondetection and about 15% over the pulse phase. Fitting the phase-resolved spectro-polarimetric data with the rotating vector model allowed us to estimate the pulsar inclination (130 & DEG;, which is in good agreement with the orbital inclination), the position angle (75 & DEG;) of the pulsar spin axis, and the magnetic obliquity (& SIM;74 & DEG;). This makes GRO J1008-57 the first confidently identified nearly orthogonal rotator among X-ray pulsars. We discuss our results in the context of the neutron star atmosphere models and theories of the axis alignment of accreting pulsars.
2023
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/05
English
Con Impact Factor ISI
accretion; accretion disks; magnetic fields; pulsars; individual; GRO J1008-57; stars; neutron; X-rays; binaries
Tsygankov, S., Doroshenko, V., Mushtukov, A., Poutanen, J., Di Marco, A., Heyl, J., et al. (2023). X-ray pulsar GRO J1008-57 as an orthogonal rotator. ASTRONOMY & ASTROPHYSICS, 675 [10.1051/0004-6361/202346134].
Tsygankov, S; Doroshenko, V; Mushtukov, A; Poutanen, J; Di Marco, A; Heyl, J; La Monaca, F; Forsblom, S; Malacaria, C; Marshall, H; Suleimanov, V; Svo...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/339552
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