We consider the Einstein-scalar-Gauss-Bonnet theory in the presence of a cosmological
constant Λ, either positive or negative, and look for novel, regular black-hole solutions with a …

We consider the Einstein-scalar-Gauss-Bonnet theory, and study the case where a negative
cosmological constant is replaced by a more realistic, negative scalar-field potential. We …

A bstract We establish a no inner-horizon theorem for black holes with charged scalar hairs.
Considering a general gravitational theory with a charged scalar field, we prove that there …

A scalar field non-minimally coupled to certain geometric [or matter] invariants which are
sourced by [electro] vacuum black holes (BHs) may spontaneously grow around the latter …

We discuss two spherically symmetric solutions admitted by the Horndeski (or scalar-tensor)
theory in the context of Solar System and astrophysical scenarios. One of these solutions is …

A step-by-step approach is followed to study cosmic structures in the context of Brans-Dicke
theory with positive cosmological constant Λ and parameter ω. First, it is shown that regular …

We prove the nonexistence of massive scalar, vector and tensor hairs outside the surface of
a static and stationary compact reflecting star. Our result is the extension of the no-hair …

In this chapter, we study special photon orbits defined by means of Killing vectors and
present a framework based on the properties of such null orbits. For concreteness, we …

We prove a no charged scalar hair theorem for static black holes in de-Sitter spacetime in
the region between the event horizon and the cosmological horizon. The proof does not …

Relativistic gravitational collapse provides a theoretical framework within the general theory
of relativity (GR) to explain how space-time singularities and black holes originate from …