Conserved charges of 3D black holes in ENMG theory from Wald formalism

We will consider a toy model of generalization of three-dimensional (3D) gravity in the presence of higher curvature corrections known as extended new massive gravity (ENMG). By employing the Wald approach in the context of covariant phase space formalism, we compute the conserved charges of 3D rotating black holes in ENMG. In fact, we will obtain exact expressions for the mass and angular momentum of two kinds of rotating black holes the so called Banados-Teitelboim-Zanelli (BTZ) and warped anti-de Sitter (WAdS3) black holes. We show that these physical quantities not only satisfy the Smarr-like formula for the mass of a black hole but also fulfill the first law of black holes thermodynamics.