We study a number of well-motivated theories modified gravity with the common overarching theme that they predict existence compact objects such as black holes and wormholes endowed scalar hair. compute shadow radius resulting demonstrate hole images M87$^*$ or more recent SgrA$^*$ by Einstein Horizon Telescope (EHT) collaboration may provide powerful way to constrain deviations metric function...

The acceleration of the cosmic expansion may be due to a new component of physical energy density or a modification of physics itself. Mapping the expansion of cosmic scales and the growth of large scale structure in tandem can provide insights to distinguish between the two origins. Using Minimal Modified Gravity (MMG)—a single parameter gravitational growth index formalism to parametrize modi...

We extend a recently developed numerical code to obtain stationary, axisymmetric solutions that describe rotating black hole spacetimes in wide class of modified theories gravity. The utilizes relaxed Newton-Raphson method solve the full nonlinear Einstein's equations on two-dimensional grid with Newton polynomial finite difference scheme. validate this by considering static and holes general r...

We review the status of a certain (infinite) class of four-dimensional generally covariant theories propagating two degrees of freedom that are formulated without any direct mention of the metric. General relativity itself (in its Plebański formulation) belongs to the class, so these theories are examples of modified gravity. We summarize the current understanding of the nature of the modificat...

For distant observers, black holes are trapped spacetime domains bounded by apparent horizons. We review properties of the near-horizon geometry emphasizing consequences two common implicit assumptions semiclassical physics. The first is a consequence cosmic censorship conjecture, namely, that curvature scalars finite at second horizons form in asymptotic time (i.e. according to observers), pro...