Observational signatures of rotating black holes in the semiclassical gravity with trace anomaly

In a recent work by Fernandes[Phys.Rev.D 108(6),L061502(2023)],an exact stationary and axisymmetric solution was discovered in semiclassical gravity with type-A trace anomaly.This was identified as a quantum-corrected version of the Kerr black hole.In this study,we explore the observational signatures of this black hole solution.Our investigation reveals that prograde and retrograde light rings exist,whose radii increase monotonically with the coupling parameterα.Whenαis negative,the shadow area for the quantum-corrected black hole is smaller than that of the Kerr black hole,whereas whenαis positive,the area is larger.For a near-extremal black hole,its high-spin feature(the NHEKline)is found to be highly susceptible to disruption byα.Furthermore,we discuss the images of the quantum-corrected black hole in the presence of a thin accretion disk and compare them to those of the Kerr black hole.Our study highlights the importance of near-horizon emission sources in detecting the effects of quantum corrections by black hole images.

Influence of quantum correction on black hole shadows, photon rings, and lensing rings

We calculate photon sphere r_(ph) and critical curve b_(c) for a quantum corrected Schwarzschild black hole,finding that they violate universal inequalities proved for asymptotically flat black holes that satisfy the null energy condition in the framework of Einstein gravity.This violation seems to be a common phenomenon when considering quantum modification of Einstein gravity.Furthermore,we study the shadows,lensing rings,and photon rings in the quantum corrected Schwarzschild black hole.The violation leads to a larger bright lensing ring in the observational appearance of the thin disk emission near the black hole compared with the classical Schwarzschild black hole.Our analysis may provide observational evidence for the quantum effect of general relativity.