Related papers: Scalar field configurations supported by charged c…
We do a systematic study of the phases of gravity coupled to an electromagnetic field and charged scalar in flat space, with box boundary conditions. The scalar-less box has previously been investigated by Braden, Brown, Whiting and York…
The existence of a regular non-trivial scalar field in the background of an asymptotically flat static reflecting star is discussed. The scalar field is assumed to be conformally coupled to the outside matter. The induced scalar charge is…
A complex scalar field on a charged black hole in a cavity is known to experience a superradiant instability. We investigate possible final states of this instability. We find hairy black hole solutions of a fully coupled system of Einstein…
We prove the non existence 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 theorem for black holes to horizonless compact…
It has been shown that the synergy of a scalar field coupling with both the Ricci scalar and the Gauss-Bonnet invariant significantly affects the properties of scalarized black holes and neutron stars, including their domain of existence…
In a recent paper, Hod started a study on no scalar hair theorem for asymptotically flat spherically symmetric neutral horizonless reflecting compact stars. In fact, Hod's approach only rules out massive scalar fields. In the present paper,…
We reexamine the static and spherical symmetric compact star configuration in the $R^2$ model of the $F(R)$ gravity theory. With asymptotic solutions for the additional scalar degrees of freedom, we refine analysis on the external geometry…
In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and…
For a theory in which a scalar field $\phi$ has a nonminimal derivative coupling to the Einstein tensor $G_{\mu \nu}$ of the form $\phi\,G_{\mu \nu}\nabla^{\mu}\nabla^{\nu} \phi$, it is known that there exists a branch of static and…
Can a black hole that suffers a superradiant instability evolve towards a 'hairy' configuration which is stable? We address this question in the context of Einstein-charged scalar field theory. First, we describe a family of static black…
We study the instability of near extremal and extremal four-dimensional AdS charged hairy black hole to radial neutral massive and charged massless scalar field perturbations. We solve the scalar field equation by using the improved…
In this paper, the behaviour of a charged massive scalar test field in the background of a Kerr-Sen black hole is investigated. A kind of stationary solutions, dubbed scalar clouds, are obtained numerically and expressed by the existence…
The physical properties of bound-state charged massive scalar field configurations linearly coupled to a spherically symmetric charged reflecting shell are studied {\it analytically}. To that end, we solve the Klein-Gordon wave equation for…
We investigate the photonsphere in the background of regular asymptotically flat compact stars. The analysis includes the general hairy compact star considering the matter fields' backreaction on the metric in various gravity theories. We…
We study scalarization of spherically symmetric neutral reflecting shells in the scalar-tensor gravity. We consider neutral static massless scalar fields non-minimally coupled to the Gauss-Bonnet invariant. We obtain a relation representing…
Some quantum-gravity theories suggest that the absorbing horizon of a classical black hole should be replaced by a reflective surface which is located a microscopic distance above the would-be classical horizon. Instead of an absorbing…
We study the classical radiation emitted by free-falling charges in de Sitter spacetime coupled to different kinds of fields. Specifically we consider the cases of the electromagnetic field, linearized gravity and scalar fields with…
We discuss radiation fields in a compact space of finite size instead of that in a cavity for investigating the coupled atom-radiation field system. Representations of $T(1)\times SO(4)$ group are used to give a formulation for kinematics…
We obtain fields of a relativistic radiating star of non-static mass in the framework of higher dimensional spacetime. Assuming energy-momentum tensor in Higher dimensions analogous to that considered by Vaidya in 4 dimensions we obtain…
A four-dimensional static black hole solution of Einstein equation conformally coupled to a massive and self interacting scalar field is obtained. A nontrivial scalar solution proposes a weak scalar hair. A dressed black hole shows a trace…