## [2003.08927] Rotating black holes in the novel $4D$ Einstein-Gauss-Bonnet gravity

 Authors: Rahul Kumar, Sushant G. Ghosh Abstract: Recently, Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] formulated the $4D$ novel Einstein-Gauss-Bonnet gravity (EGB), by rescaling the Gauss-Bonnet (GB) coupling $\alpha/(D-4)$ and taking the limit $D \rightarrow 4$, which preserves the number of degrees of freedom thereby free from the Ostrogradsky instability. The theory admits spherically symmetric black holes generalizing the Schwarzschild black holes that are free form the singularity problems. We obtain the rotating counterparts of these spherically symmetric black holes and discuss their horizon properties and shadow cast. The effects of the GB coupling parameter on the shape and size of shadows are investigated in the context of recent M87* observations from the EHT. Interestingly, for a given parameter set, the apparent size of the shadow decreases and gets more distorted due to the GB coupling parameter. We find that within the finite parameter space, e.g. for $a=0.1$, $\alpha\leq 0.00394$, and within the current observational uncertainties, the rotating black holes of the $4D$ novel EGB gravity are consistent with the inferred features of M87* black hole shadow. [PDF]  [PS]  [BibTex]  [Bookmark]

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