## Testing Loop Quantum Gravity from Observational Consequences of Nonsingular Rotating Black Holes

Loop quantum gravity (LQG) is one of the promising candidates of quantum gravity in modern theoretical physics. However, the lack of rotating black hole models, where are typically found in nature, in LQG substantially hinders the progress of testing LQG from observations. In this Letter, we construct a rotating spacetime as an effective rotating black hole model inspired by LQG. The solution is nonsingular everywhere and it reduces to the Kerr black hole asymptotically. In different regions of the parameter space, the solution describes a wormhole, or a black hole with one or two event horizons. In particular, the black hole model with two horizons possesses a very interesting causal structure (Fig. 1). We then show how fundamental parameters of LQG can be constrained by the observational implications of the shadow cast by this object (Fig. 2). It is argued that the causal structure of our solution is agnostic about specific details of the ansatz under consideration, and therefore captures universal features of an effective rotating, nonsingular black hole in LQG. The results are published in Phys. Rev. Lett. 126 (2021) 18, 181301.

Journal Links: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.181301