Finite-Distance Imaging of Relativistic Equilibrium Tori around Genuine Kerr--Bertotti--Robinson Black Holes
Abstract
We calculate finite-distance images of stationary, pressure-supported tori around genuine, electrically neutral Kerr--Bertotti--Robinson black holes using general relativistic ray tracing with gray emission and absorption. The emitting volume is bounded by a constant-specific-angular-momentum equilibrium free surface, and the observer is placed at a radius of 50M. Along the investigated external-field sequence, integrated brightness and apparent size both increase strongly as the field modifies the equilibrium source and photon propagation. Higher torus filling has a different effect: in a representative sequence, brightness grows by a factor of $5.9$ while the intensity-weighted image size increases by only 10%. Increasing viewing inclination enhances lateral brightness contrast. Stronger self-absorption can coexist with higher absolute brightness because emission and absorption scale together in the adopted gray prescription. At common pressure center and filling, increasing the dimensionless spin from $0.5$ to $0.95$ dims the retrograde sequence by a factor of about $7$ as its equilibrium contracts, whereas prograde brightness changes by only 2%. These contrasting responses show how the equilibrium boundary, fluid motion, and optical depth jointly shape the brightness, scale, and asymmetry of finite-distance torus images.
Related
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BibTeX
@misc{yan2026finitedistance,
title = {{Finite-Distance Imaging of Relativistic Equilibrium Tori around Genuine Kerr--Bertotti--Robinson Black Holes}},
author = {Hao-Peng Yan and Xiang-Qian Li and Xiao-Jun Yue},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34331},
eprint = {2610.34331},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34331},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Finite-Distance Imaging of Relativistic Equilibrium Tori around Genuine Kerr--Bertotti--Robinson Black Holes
AU - Hao-Peng Yan
AU - Xiang-Qian Li
AU - Xiao-Jun Yue
PY - 2026
DA - 2026/10/25
PB - arXiv
DO - 10.48550/arxiv.2610.34331
UR - https://arxiv.org/abs/2610.34331
AB - We calculate finite-distance images of stationary, pressure-supported tori around genuine, electrically neutral Kerr--Bertotti--Robinson black holes using general relativistic ray tracing with gray emission and absorption. The emitting volume is bounded by a constant-specific-angular-momentum equilibrium free surface, and the observer is placed at a radius of 50M. Along the investigated external-field sequence, integrated brightness and apparent size both increase strongly as the field modifies the equilibrium source and photon propagation. Higher torus filling has a different effect: in a representative sequence, brightness grows by a factor of $5.9$ while the intensity-weighted image size increases by only 10%. Increasing viewing inclination enhances lateral brightness contrast. Stronger self-absorption can coexist with higher absolute brightness because emission and absorption scale together in the adopted gray prescription. At common pressure center and filling, increasing the dimensionless spin from $0.5$ to $0.95$ dims the retrograde sequence by a factor of about $7$ as its equilibrium contracts, whereas prograde brightness changes by only 2%. These contrasting responses show how the equilibrium boundary, fluid motion, and optical depth jointly shape the brightness, scale, and asymmetry of finite-distance torus images.
ER -