Related papers: How do scalar-field dark matter haloes react to or…
This note tackles the problem of the backscattering of a mass-less scalar field in the case of Schwarzschildean space-time. It shows that the effect depends both on a distance from the horizon and on the wave length. The obtained estimates…
Scalar field self-force effects on a scalar charge orbiting a Reissner-Nordstr\"om black hole are investigated. The scalar wave equation is solved analytically in a post-Newtonian framework, and the solution is used to compute the…
The scalar ``cosmon'' field mediating quintessence influences the dynamics of extended objects in the universe. We discuss cosmon lumps -- spherically symmetric solutions for the scalar field coupled to gravity. The two integration…
We analyze the spherically symmetric Einstein field equation with a massless complex scalar field. We can use the Newtonian solutions to fit the rotation curve data of spiral and dwarf galaxies. From the general relativistic solutions, we…
We summarize results from a study of spherically symmetric collapse of a {\it charged} (complex) massless scalar-field \cite{Hod}. We present an analytic argument which conjecture the generalization of the mass-scaling relation and echoing…
A massless scalar field minimally coupled to the gravitational field in a simplified spherical symmetry is discussed. It is shown that, in this case, the solution found by Roberts, describing a scalar field collapse, is in fact the most…
Using observational data for a sample of dark matter dominated galaxies and two cluster of galaxies, we have found that the central halo density does not depend on its mass, and the core radius is roughly proportional to the maximum…
We investigated scalarization in dark matter stars. In scalar tensor theories, the coupling between matter and a scalar field generates an effective mass, which is known to trigger the growth of the scalar field in stars and black holes…
(Context) In a Universe dominated by dark matter, halos are continuously accreting mass (violently or not) and such mechanism affects their dynamical state. (Aims) The evolution of dark matter halos in phase-space, and using the phase-space…
Gravastars are configurations of compact singularity-free gravitational objects which are interesting alternatives to classical solutions in the strong gravitational field regime. Although there are no static star-like solutions of the…
We study perturbations of a complex scalar field during reheating with no self-interaction in the regime $ \mu \gg H$, when the scalar field has a fast oscillatory behaviour (close to a pressure-less fluid). We focus on the precise…
Self-interacting dark matter has been proposed as a solution to small scale problems in cosmological structure formation, and hints of dark matter self scattering have been observed in mergers of galaxy clusters. One of the simplest models…
The effect of halo substructures on galaxy rotation curves is investigated in this paper using a simple model of dark matter clustering. A dark matter halo density profile is developed based only on the scale free nature of clustering that…
We investigate the orientation of the axes and angular momentum of dark matter halos with respect to their neighboring voids using high resolution N-body cosmological simulations. We find that the minor axis of halos tends to be aligned…
Recent, very accurate simulations of galaxy formation have revealed that the standard cold dark matter model has great difficulty in explaining the detailed structure of galaxies. One of the major problems is that galactic halos are too…
Self-interacting dark matter may have striking astrophysical signatures, such as observable offsets between galaxies and dark matter in merging galaxy clusters. Numerical N-body simulations used to predict such observables typically treat…
Cosmological N--body simulations have revealed a remarkable similarity in the structure of dark matter halos formed in hierarchically clustering universes. Regardless of halo mass, cosmological parameters, and power spectrum of initial…
We discuss the dynamics and phenomenology of an oscillating scalar field coupled to the Higgs boson that accounts for the dark matter in the Universe. The model assumes an underlying scale invariance such that the scalar field only acquires…
Diverse cosmological and astrophysical observations strongly hint at the presence of dark matter and dark energy in the Universe. One of the main goals of Cosmology is to explain the nature of these two components. It may well be that both…
A numerical study of the evolution of a massless scalar field in the background of rotating black holes is presented. First, solutions to the wave equation are obtained for slowly rotating black holes. In this approximation, the background…