Ultralight bosons and axion-like particles appear naturally in different scenarios and could
solve some long-standing puzzles. Their detection is challenging, and all direct methods …

The wide applications of higher dimensional gravity and gauge/gravity duality have fuelled
the search for new stationary solutions of the Einstein equation (possibly coupled to matter). …

A wave impinging on a Kerr black hole can be amplified as it scatters off the hole if certain
conditions are satisfied, giving rise to superradiant scattering. By placing a mirror around the …

We provide strong evidence that, up to 99.999% of extremality, Kerr-Newman black holes (KNBHs)
are linear mode stable within Einstein-Maxwell theory. We derive and solve, …

Superradiance in black hole spacetimes can trigger instabilities. Here we show that, due to
superradiance, small Kerr–anti-de Sitter black holes are unstable. Our demonstration uses a …

Bizon and Rostworowski have recently suggested that anti-de Sitter spacetime might be
nonlinearly unstable to transferring energy to smaller and smaller scales and eventually forming …

Gravitational wave solutions to Einstein’s equations and their generation are examined in D-dimensional
flat spacetimes. First the plane wave solutions are analyzed; then the wave …

We present the first examples of black holes with only one Killing field. The solutions describe
five dimensional AdS black holes with scalar hair. The black holes are neither stationary …

Despite the recent evidence that anti-de Sitter (AdS) spacetime is nonlinearly unstable, we
argue that many asymptotically AdS solutions are nonlinearly stable. This includes geons, …

Black holes in anti-de Sitter (AdS) backgrounds play a pivotal role in the gauge/gravity duality
where they determine, among other things, the approach to equilibrium of the dual field …