Study models intensity and polarization of rotating Konoplya-Zhidenko black holes with thick accretion flows

Researchers used analytical ballistic-approximation models and numerical ray-tracing to examine the shadow and linear-polarization signatures of a rotating Konoplya-Zhidenko black hole embedded in a thick, optically thin accretion flow. The simulated images display a bright outer ring, produced by higher-order photon trajectories that loop around the black hole, and an inner dark region corresponding to the event horizon.

Increasing the deformation parameter η expands the size of the bright ring without markedly altering its shape, while higher spin values and larger observer inclination angles enhance asymmetry, making the left side of the ring significantly brighter than the right. The authors attribute this effect to frame dragging and relativistic Doppler boosting.

Polarization analysis shows a lower degree of linear polarization within the bright-ring region, whereas polarization vectors extend across the entire image plane. The pattern differs from predictions for thin-disk models, suggesting that thick-disk geometry leaves a measurable imprint on both intensity and polarization.

"The observed intensity and polarization signatures can serve as effective probes of the underlying spacetime geometry and near-horizon accretion dynamics," the study concludes.

The findings indicate that future high-resolution observations could discriminate between Kerr and non-Kerr black hole metrics by comparing measured shadow and polarization structures with model predictions.