Testing strong gravity and fundamental physics using black hole shadows

Che-Yu Chen^1*

¹Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Che-Yu Chen, email:b97202056@gmail.com

Testing strong gravity regimes such as the vicinity of black holes using their shadow images is likely to be attainable with the future developments of observing technology. In this work, we propose a class of Kerr-like rotating black holes, whose Z₂ symmetry is generically broken. We focus on the possibility that such a violation of Z₂ symmetry is induced by the spin of the black hole. Within a theory-agnostic framework, the violation of the Z₂ symmetry is parametrized by a single parameter. This class of Kerr-like spacetimes could be a good approximation to general black hole solutions in effective low-energy theories of a fundamental quantum theory of gravity with parity-violating interactions. We investigate how the shadow contour of the Kerr-like black hole and the associated observables are affected by the deviation parameter. It turns out that the parameter has merely little degeneracy with the spin of the black hole, meaning that it can be constrained by the apparent size of the M87* shadow recently observed by the Event Horizon Telescope.

Keywords: black hole, gravity, black hole shadow, general relativity