Pedro Cunha, Carlos Herdeiro and Eugen Radu studied how one can distinguish new theories of gravity by using black hole images. Their results are now Physical Review Letter cover!
Read the work here:
Pedro V. P. Cunha, Carlos A. R. Herdeiro, and Eugen Radu, Spontaneously Scalarized Kerr Black Holes in Extended Scalar-Tensor–Gauss-Bonnet Gravity, Physical Review Letters 123, 011101 (2019).