相关论文: Spontaneous scalarization in generalised scalar-te…
In the present paper we construct novel non-topological, spontaneously scalarized neutron stars in multi-scalar Gauss-Bonnet gravity with maximally symmetric target space, and nontrivial map $\varphi:spacetime \rightarrow target\ space$.…
In the present paper we study the onset of the spin-induced scalarization of a Kerr black hole in scalar-Gauss-Bonnet gravity with a massive scalar field. Our approach is based on a (2+1) time evolution of the relevant linearized scalar…
We consider a scalar field coupled to the torsion in Teleparallel Gravity with a coupling function that does not allow for a tachyonic instability to occur, and it leads to the formation of new black holes with scalar hair. The scalarized…
In general relativity, astrophysical black holes are simple objects, being described by just their mass and spin. These simple solutions are not exclusive to general relativity, as they also appear in theories that allow for an extra scalar…
We investigate spin-induced scalarization of Kerr black holes in an Einstein-scalar-Gauss-Bonnet (EsGB) model that does not admit a linear tachyonic instability of the scalar-free solution. The scalarization mechanism is therefore genuinely…
We analyze how a scalar field can affect the chaotic behaviour of homogeneous and isotropic Bianchi IX cosmologies. It is known that a massless, minimally coupled scalar field removes the chaos. However, in more general Horndeski theories,…
A model in which black hole scalarization occurs for supermassive black holes, while their less massive counterparts remain unscalarized, has been recently proposed. We explore whether this model can emerge from an effective field theory…
We derive the tensor gravitational waveform generated by a binary of nonspinning compact objects (black holes or neutron stars) in a general class of scalar-tensor theories of gravity. The waveform is accurate to second post-Newtonian order…
We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero…
Some models (such as the Skyrme model, a low-energy effective field theory for QCD) suggest that the high-density matter prevailing in neutron star interiors may be significantly anisotropic. Anisotropy is known to affect the bulk…
Scalar-tensor theories with a scalar field coupled to the Gauss-Bonnet invariant can evade no-hair theorems and allow for non-trivial scalar profiles around black holes. This coupling is characterized by a length scale $\lambda$, which, in…
We report a new black hole scalarization mechanism and disclose novel dynamical critical phenomena in the process of the nonlinear accretion of the scalar field into black holes. The accretion process can transform a seed black hole into a…
Many classes of extended scalar-tensor theories predict that dynamical instabilities can take place at high energies, leading to the formation of scalarized neutron stars. Depending on the theory parameters, stars in a scalarized state can…
Studying a certain sub class of higher order Horndeski (scalar-tensor) theories we discuss a method discovered recently permitting analytic black hole solutions with a non trivial and regular scalar field. One of the solutions found has de…
We consider scalar fields which are coupled to Einstein gravity with a negative cosmological constant, and construct periodic solutions perturbatively. In particular, we study tachyonic scalar fields whose mass is at or above the…
Scalar-tensor theories of gravity are natural phenomenological alternatives to General Relativity, where the gravitational interaction is mediated by a scalar degree of freedom, besides the usual tensor gravitons. In regions of the…
Recently it was pointed out that in shift-symmetric scalar-tensor theories a black hole can have nontrivial scalar hair which depends linearly on time. We develop black hole perturbation theory for such solutions and compute the quadratic…
In the present paper, we construct spontaneously scalarized rotating black hole solutions in dynamical Chern-Simons (dCS) gravity by following the scalar field evolution in the decoupling limit. For the range of parameters where the Kerr…
We study the superradiant instability in scalar-tensor theories of gravitation, where matter outside a black hole provides an effective mass to the scalar degree of freedom of the gravitational sector. We discuss this effect for arbitrarily…
No-hair theorems for scalar-tensor theories imply that the trivial scalar field configuration is the unique configuration around stationary black hole spacetimes. The most basic assumption in these theorems is that a constant scalar…