One century after its formulation, Einstein's general relativity (GR) has made remarkable
predictions and turned out to be compatible with all experimental tests. Most of these tests …

The advent of gravitational waves and black hole imaging has opened a new window into
probing the horizon scale of black holes. An important question is whether string theory …

The dawn of the twenty-first century came with very positive prospects for gravity, cosmology,
and astrophysics. Technological progress made it possible for cosmology to enter to its …

Abstract The LIGO and Virgo Interferometers have so far provided 11 gravitational-wave
(GW) observations of black-hole binaries. Similar detections are bound to become very …

Black holes (BHs) in general relativity (GR) are very simple objects. This property, that goes
under the name of'no-hair', has been refined in the last few decades and admits several …

Within general relativity, the unique stationary solution of an isolated black hole is the Kerr
spacetime, which has a peculiar multipolar structure depending only on its mass and spin …

A bstract We construct a family of non-supersymmetric extremal black holes and their
horizonless microstate geometries in four dimensions. The black holes can have finite …

A bstract We explain in detail how to calculate the gravitational mass and angular
momentum multipoles of the most general non-extremal four-dimensional black hole with …

We present an investigation of spinning black holes in Einstein–Gauss-Bonnet–dilaton
(EGBd) theory. The solutions are found within a nonperturbative approach, by directly …

A bstract We extend and refine a general method to extract the multipole moments of
arbitrary stationary spacetimes and apply it to the study of a large family of regular …