Spin-disc misalignment drives periodic accretion and pulse profile asymmetry in X-ray pulsars

[2608.27691] Spin-disc misalignment drives periodic accretion and pulse profile asymmetry in X-ray pulsars Skip to main content Search Submit Donate Log in Astrophysics > High Energy Astrophysical Phenomena arXiv:2608.27691 (astro-ph) [Submitted on 27 Aug 2026] Title: Spin-disc misalignment drives periodic accretion and pulse profile asymmetry in X-ray pulsars Authors: A. A. Mushtukov , V. Ganesh , S. S. Tsygankov , S. Portegies Zwart , A. Palyam View PDF HTML (experimental) Abstract: We investigate magnetospheric accretion in disc-fed X-ray pulsars assuming that the neutron star spin axis is not perpendicular to the disc plane. We focus on X-ray pulsars, where a geometrically thin disc is truncated far from the stellar surface the channelled part of the accretion flow is expected to be guided by the large-scale dipolar magnetic field after coupling to it near the disc-magnetosphere boundary. Using numerical simulations of plasma motion from the inner disc edge to the neutron star surface, we show that a finite inclination between the disc normal and the stellar spin axis leads to periodic modulation of the mass accretion rate onto the magnetic poles even for a steady mass supply through the disc. This purely geometrical effect arises because stellar rotation changes the orientation of the magnetosphere relative to the disc, producing phase-dependent mass loading of magnetic field lines. The amplitude and shape of the modulation are determined by the system geometry and by the ratio of the stellar spin period to the flow time through the magnetosphere. The resulting variability affects the structure and luminosity of emitting regions near the neutron star surface and leads to asymmetric X-ray pulse profiles. Even without intrinsic asymmetries of the emission regions, this mechanism breaks the time-reversal symmetry expected for stationary accretion and naturally contributes to the observed asymmetry of pulse profiles and phase-resolved spectral features. The effect may also be relevant for ULX pulsars, where intrinsic accretion rate modulation can help preserve strong pulsations in the presence of geometric beaming. Comments: accepted for publication in MNRAS, 14 pages, 7 figures Subjects: High Energy Astrophysical Phenomena (astro-ph.HE) ; Solar and Stellar Astrophysics (astro-ph.SR) Cite as: arXiv:2608.27691 [astro-ph.HE] (or arXiv:2608.27691v1 [astro-ph.HE] for this version) https://doi.org/10.48550/arXiv.2608.27691 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Alexander A. Mushtukov [ view email ] [v1] Thu, 27 Aug 2026 20:27:29 UTC (2,366 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Additional Features Audio Summary Current browse context: astro-ph.HE < prev | next > new | recent | 2026-08 Change to browse by: astro-ph astro-ph.SR References & Citations INSPIRE HEP SciX Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab)

Related documents

• Spin-disc misalignment drives periodic accretion and pulse profile asymmetry in X-ray pulsars#779614
• Pulse profiles of tall accretion columns in X-ray pulsars#1117057
• The X-Ray Polarimetry View of the Accreting Pulsar Cen X-3#183866
• Detection of hard X-ray pulsations in non-ULX X-ray pulsar 3X J0042 in M31#997693
• Black hole-neutron star binaries with high spins and large mass asymmetries: III. Properties of the ejected material and its electromagnetic signatures#1105114