相关论文: Parametric instability in scalar gravitational fie…

Neutron stars are ideal astrophysical sources to probe general relativity due to their large compactnesses and strong gravitational fields. For example, binary pulsar and gravitational wave observations have placed stringent bounds on…

In this work, we present a detailed investigation of gravastars within the framework of scalar-tensor theories, emphasizing both the background and perturbed levels for trivial and non trivial scalar field. We derive and analyze the…

The pulse profile from a neutron star in scalar-tensor theory of gravity is examined for several stellar models, where we assume the existence of the antipodal hot spots on the neutron star based on the polar cap model. Then, we find that…

We investigate the possibility that electromagnetic fluctuations are amplified in expanding universe by parametric resonance, during the oscillatory regime of a scalar field to which they are coupled. We consider scalar electrodynamics and…

Binary neutron star mergers provide a laboratory for probing fundamental physics through their gravitational-wave emission and electromagnetic counterparts. In particular, they may allow us to explore signatures of physics beyond the…

We study the time evolution of a complex scalar field in the symmetry broken phase in the presence of oscillating spacetime metric background. In our (2+1)-dimensional simulations, we show that the spacetime oscillations can excite an…

We consider a scalar-tensor theory of gravitation with the scalar source being the trace of the stress-energy tensor of the scalar field itself and matter. We obtain an example of a numerical solution of the cosmological equations which…

Solutions for scalar fields superdense gravitating systems of flat, open and closed type obtained in the frame of gauge theories of gravitation are discussed. Properties of these systems in dependence on parameter $\beta$ and initial…

We study the scintillation produced by time-varying gravitational fields within scalar-tensor theories of gravity. The problem is treated in the geometrical optics approximation for a very distant light source emitting quasi plane…

The possible existence of a complex metric tensor field is studied. We show that an effective scalar field is induced by an overall phase component of the complex metric tensor. The corresponding gauge field is shown to be a tachyon.…

Using a scalar field as an intrinsic 'clock' while investigating the dynamics of gravitational systems has been successfully pursued in various researches on the border between classical and quantum gravity. The objective of our research…

The recent observations of neutron star mergers have changed our perspective on scalar- tensor theories of gravity, favouring models where gravitational waves travel at the speed of light. In this work we consider a scalar-tensor set-up…

We clarify the properties of the behavior of classical cosmological perturbations when the Universe experiences a bounce. This is done in the simplest possible case for which gravity is described by general relativity and the matter content…

The best motivated alternatives to general relativity are scalar-tensor theories, in which the gravitational interaction is mediated by one or several scalar fields together with the usual graviton. The analysis of their various…

The dynamical consequences of a bimetric scalar-tensor theory of gravity with a dynamical light speed are investigated in a cosmological setting. The model consists of a minimally-coupled self-gravitating scalar field coupled to ordinary…

We review the results in our recent works on the generation of strong magnetic fields in compact stars driven by the parity violating electroweak interactions between background fermions. The cases of a neutron star, a hybrid star, and a…

Given that gravitational waves are the future probes of the universe, it is important to test various physical effects of these on matter. This article explores the first-order perturbation, caused by a planar gravitational wave, on…

General relativity probably is not the definitive theory of gravity, due a number or issues, both from the theoretical and from the observational point of view. Alternative theories of gravity were conceived to extend general relativity and…

That preferred-frame theory accounts for special relativity and reduces to it if the gravitation field cancels. Starting from an interpretation of gravity as a pressure force, it is based on just one scalar field. This scalar gives the…

In the present paper, we numerically construct new non-topological, spontaneously scalarized neutron stars in the tensor-multi-scalar theories of gravity whose target space is a three-dimensional maximally symmetric space, namely either…