Optical images of the Kerr-Sen black hole and thin accretion disk

TL;DR

This study models the optical appearance of Kerr-Sen black holes with thin accretion disks, revealing how spin, charge, and viewing angle influence observable features like shadow distortion and redshift, aiding future astronomical observations.

Contribution

It provides a detailed ray-tracing analysis of Kerr-Sen black hole images, emphasizing the effects of spin and charge on observable properties, which advances theoretical understanding of such black holes.

Findings

Spin significantly distorts the black hole's shadow more than charge.

Observer inclination angle critically affects redshift distribution.

Higher intensity observed at 86 GHz compared to 230 GHz.

Abstract

This paper investigates the observable properties of a Kerr-Sen black hole surrounded by a thin accretion disk, focusing on the impact of the black hole's spin and charge on the image. Using ray-tracing techniques, we conduct a detailed analysis of the black hole's image, redshift distribution, and intensity distributions at different observation frequencies. The results demonstrate that spin has a more significant effect on the distortion of the inner shadow than charge, and the observer's inclination angle plays a critical role in shaping the redshift distribution, especially near the innermost stable circular orbit. Additionally, the intensity is found to be higher at 86 GHz than at 230 GHz. This study highlights the crucial role of the accretion disk's geometry in determining the black hole's image and redshift effects, thereby providing a refined theoretical framework to guide future observational efforts targeting the Kerr-Sen black hole and its electromagnetic signals.