Profiles of emission lines generated by rings orbiting braneworld Kerr black holes

TL;DR

This paper investigates how the tidal charge in braneworld Kerr black holes influences the spectral line profiles from orbiting radiating tori, revealing effects of charge, inclination, and gravitational lensing on line shape and extension.

Contribution

It introduces the impact of tidal charge on spectral line profiles in braneworld Kerr black holes, highlighting the effects of charge, inclination, and gravitational lensing.

Findings

Negative tidal charge flattens and widens lines with stronger blue flux.

Line extension increases with radius and inclination angle.

Strong lensing causes humps in line profiles at high inclination angles.

Abstract

In the framework of the braneworld models, rotating black holes can be described by the Kerr metric with a tidal charge representing the influence of the non-local gravitational (tidal) effects of the bulk space Weyl tensor onto the black hole spacetime. We study the influence of the tidal charge onto profiled spectral lines generated by radiating tori orbiting in vicinity of a rotating black hole. We show that with lowering the negative tidal charge of the black hole, the profiled line becomes to be flatter and wider keeping their standard character with flux stronger at the blue edge of the profiled line. The extension of the line grows with radius falling and inclination angle growing. With growing inclination angle a small hump appears in the profiled lines due to the strong lensing effect of photons coming from regions behind the black hole. For positive tidal charge ($b>0$) and high inclination angles two small humps appear in the profiled lines close to the red and blue edge of the lines due to the strong lensing effect. We can conclude that for all values of $b$, the strongest effect on the profiled lines shape (extension) is caused by the changes of the inclination angle.