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Abstract
A large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer (IXPE) in the high-soft emission state of the black hole X-ray binary 4U 1630–47. The highly significant detection (at ≈50σ confidence level) of an unexpectedly high polarization, rising from ∼6% at 2 keV to ∼10% at 8 keV, cannot be easily reconciled with standard models of thin accretion disks. In this work, we compare the predictions of different theoretical models with the IXPE data and conclude that the observed polarization properties are compatible with a scenario in which matter accretes onto the black hole through a thin disk covered by a partially ionized atmosphere flowing away at mildly relativistic velocities.
Department
Space Science Center
Publication Date
3-1-2024
Journal Title
The Astrophysical Journal
Publisher
American Astronomical Society
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Ajay Ratheesh et al 2024 ApJ 964 77 DOI 10.3847/1538-4357/ad226e
Rights
© 2024. The Author(s).
Comments
This is an open access article published by American Astronomical Society in The Astrophysical Journal in 2024, available online: https://dx.doi.org/10.3847/1538-4357/ad226e