Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2610.35589

Gravitationally Induced Polarization-Angle Rotation in Pulsar-Black Hole Binaries

Jyotijwal Debnath·Amodio Carleo·Delphine Perrodin·Pratik Tarafdar
View original source ↗Read source document ↗Export metadata ↓

Abstract

Radio pulsars emit highly polarized radiation whose polarization properties are commonly described by the Rotating Vector Model (RVM). In this work, we investigate the effects of gravitational light bending and parallel transport on the polarization profile of a pulsar in a hypothetical binary system with a black hole (BH) companion. We combine the RVM with numerical integration of null geodesics to calculate the polarization direction along the photon trajectory and model the orbital-phase-dependent variation of the observed polarization position angle (PPA). We consider both non-spinning and spinning black hole companions and include the evolution of the orbital geometry due to relativistic spin-orbit coupling. For a non-spinning black hole, the change in the observed polarization direction arises from the geometric shift associated with gravitational light bending. For a spinning black hole, frame dragging introduces an additional geometric shift, while parallel transport produces an additional polarization rotation measured relative to our chosen reference construction. We investigate the dependence of these polarization changes on the binary parameters and the orientation of the pulsar spin. We find that gravitational light bending can significantly distort the characteristic S-shaped PPA profile, particularly near superior conjunction, and can reverse its overall sense of variation for the supermassive black hole system considered here. Relativistic spin-orbit evolution also affects the orbital-phase dependence of the polarization profile, particularly in the supermassive black hole system. These results show that relativistic photon propagation can modify both the shape and the phase dependence of pulsar polarization profiles and may provide a useful probe of the geometry of pulsar-BH binaries when such systems are discovered.

Explore related subjects

gr-qcastro-ph.HE

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Jyotijwal Debnath, Amodio Carleo, Delphine Perrodin, Pratik Tarafdar. 2026-10-26. Gravitationally Induced Polarization-Angle Rotation in Pulsar-Black Hole Binaries. https://arxiv.org/abs/2610.35589

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Frenet--Serret invariants of timelike worldlines in Kerr spacetime: chart independence, horizon crossing and null-endpoint limits

We examine the Frenet-Serret (FS) curvature kappa and first torsion tau_1 of timelike worldlines in Kerr spacetime, focusing mainly on non-Killing equatorial trajectories. Since these quantities are scalars associated with a worldline, a coordinate transformation cannot remove a divergence for the same curve. We demonstrate this by transforming a single worldline between five coordinate charts and verifying agreement of its invariants, including in an off-equatorial test. We also show why reusing the same coordinate components of the tangent vector in two charts generally describes different curves. For a non-unit tangent v with norm S = g(v,v), we derive the identity kappa squared = Q squared / S cubed - (q dot q) / S squared, where q = nabla_v v and Q = q dot v. When Q approaches a nonzero limit and q dot q remains finite, the curvature scales as |Q_0| S to the power -3/2 as the curve approaches a null endpoint. Under the additional condition that S' is nonzero, we obtain a closed expression for the limiting value of tau_1. We verify these results using exact symbolic calculations for two Kerr-Schild spirals, including one with spin parameter a greater than the mass M, for which no event horizon exists. For Killing observers, we derive closed-form expressions for kappa and tau_1 and show that both become singular at light surfaces. Finally, we distinguish FS torsion, which measures rotation relative to the acceleration direction, from gyroscope rotation rates defined using regular reference frames. For a geodesic plunge, the rotation rate relative to the principal-null frame remains finite across the horizon, while the rate relative to the Carter-plane axis agrees with Marck's precession rate. Our analysis focuses mainly on equatorial examples; a numerical comparison in double-null coordinates is left for future work.

gr-qc↗
arXiv2026

Quantum Reference Fields Transformations in Linearized Quantum Gravity

Diffeomorphism invariance is a central feature of general relativity. Without external reference structures, matter and geometry must be specified relationally, with respect to internal subsystems serving as reference frames. In quantum gravity, these reference systems must themselves be treated as quantum, motivating the use of quantum reference frames. In this work, we address how such a relational description could be formulated within linearized quantum gravity. To this purpose, we introduce quantum reference fields, i.e.,sets of four dynamical scalar fields whose stress-energy tensors enter the gravitational constraints. These fields extend the notion of quantum reference frames to local field-theoretic reference systems, allowing matter and gravitational degrees of freedom to be described relationally with respect to physical quantum systems whose states cannot be sharply peaked on definite field configurations. By generalizing the perspective-neutral construction of quantum reference frames, we show that relational, gauge invariant observables admit reduced descriptions in the perspective of each quantum reference field, and we derive the unitary transformations relating them. The resulting unitary maps implement local quantum coordinate changes between different internal perspectives, and act on the linearized gravitational field with an analogous structure to a linearized diffeomorphism, but with the classical gauge parameter replaced by a physical quantum field. Finally, we construct a relational von Neumann-type measurement scheme, showing how the corresponding reduced observables can be accessed operationally from the perspective of a quantum reference field.

gr-qc↗
arXiv2026

Sensing the Inflationary Production of Scalars

We review the mechanism by which loops of matter fields contribute to the graviton self-energy during de Sitter inflation. This self-energy is used to quantum-correct the linearized Einstein equations. A Green's function method is employed to obtain exact 1-loop corrections to the plane wave mode functions of gravitational radiation, subject to the usual ambiguity in the initial state. Conformally coupled matter, which does not experience inflationary particle production, makes only a logarithmic enhancement of the rate at which the imaginary part of the mode function goes to zero after horizon crossing. These corrections can be understood, and even summed up, using a variant of the renormalization group. However, massless, minimally coupled scalars, which experience massive inflationary particle production, induce a much stronger enhancement of the rate at which the real part of the mode function approaches a constant. One interpretation of this effect is as a shift of the inflationary Hubble parameter.

gr-qc↗