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Evidence for a Black Hole Spin-Orbit Misalignment in the X-Ray Binary Cyg X-1




TekijätZdziarski Andrzej A., Veledina Alexandra, Szanecki Michał, Green David A., Bright Joe S., Williams David R. A.

KustantajaIOP Publishing Ltd

Julkaisuvuosi2023

JournalAstrophysical Journal Letters

Tietokannassa oleva lehden nimiASTROPHYSICAL JOURNAL LETTERS

Lehden akronyymiASTROPHYS J LETT

Artikkelin numero L45

Vuosikerta951

Numero2

Sivujen määrä8

ISSN2041-8205

eISSN2041-8213

DOIhttps://doi.org/10.3847/2041-8213/ace2c9

Verkko-osoitehttps://doi.org/10.3847/2041-8213/ace2c9

Rinnakkaistallenteen osoitehttps://research.utu.fi/converis/portal/detail/Publication/180462039


Tiivistelmä

Recently, the accretion geometry of the black hole X-ray binary Cyg X-1 was probed with the X-ray polarization. The position angle of the X-ray-emitting flow was found to be aligned with the position angle of the radio jet in the plane of the sky. At the same time, the observed high polarization degree could be obtained only for a high inclination of the X-ray-emitting flow, indicating a misalignment between the binary axis and the black hole spin. The jet, in turn, is believed to be directed by the spin axis; hence, a similar misalignment is expected between the jet and binary axes. We test this hypothesis using very long (up to about 26 yr) multiband radio observations. We find a misalignment of 20°–30°. However, contrary to the earlier expectations, the jet and binary viewing angles are found to be similar, while the misalignment is seen between the position angles of the jet and the binary axis on the plane of the sky. Furthermore, the presence of the misalignment calls into question our understanding of the evolution of this binary system.


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Last updated on 2024-26-11 at 12:36