Related papers: Testing Strong-field Gravity with Quasi-Periodic O…
We study systematically the ~0.1-1200 Hz quasi-periodic oscillations (QPOs) and broad noise components observed in the power spectra of non-pulsing neutron-star and black-hole low-mass X-ray binaries. We show that among these components we…
The gravitational-wave and accretion driven evolution of neutron stars in low mass X-ray binaries and similar systems is analyzed, while the amplitude of the radiating perturbation (here assumed to be an r-mode) remains small. If most of…
One of the most dramatic discoveries made so far with the Rossi X-Ray Timing Explorer is that many accreting neutron stars with weak magnetic fields generate strong, remarkably coherent, high-frequency X-ray brightness oscillations. The…
We study the effect of superfluidity on torsional oscillations of highly magnetised neutron stars (magnetars) with a microphysical equation of state by means of two-dimensional, magnetohydrodynamical- elastic simulations. The superfluid…
We study the axial quasi-normal modes of neutron stars in scalar-tensor theories with massive scalar field including a self-interacting term in the potential. Various realistic equations of state including nuclear, hyperonic and hybrid…
The observation of the x-ray pulse profile emitted by hotspots on the surface of neutron stars offers a unique tool to measure the bulk properties of these objects, including their masses and radii. The x-ray emission takes place at the…
We consider the slowly rotating relativistic stars with a uniform angular velocity in the scalar-tensor gravity, and examine the rotational effect around such compact objects. For this purpose, we derive a 2nd order differential equation…
A study of gravitational properties of matter presents a fundamental interest. The possibility of investigation of quantum gravitational states of matter by the example of helium atom is shown. The capability of the existence of helium…
Neutron stars are the densest objects known in the Universe. Being the final product of stellar evolution, their internal composition and structure is rather poorly constrained by measurements. It is the purpose of this paper to put some…
Soft gamma-ray repeaters (SGRs) are widely understood as slowly rotating isolated neutron stars. Their generally large spin-down rates, high magnetic fields, and strong outburst energies render them different from ordinary pulsars. In a few…
Spherical neutron star models are studied within tensor-scalar theories of gravity. Particularly, it is shown that, under some conditions on the second derivative of the coupling function and on star's mass, for a given star there exist two…
We investigate induced oscillations by the gravitational field of a fast stellar object, such as a neutron star or a black-hole in a near miss collision with another star. Non-adiabatic collision conditions may lead to large amplitude…
At the supranuclear densities achieved inside a neutron star, matter may exhibit extreme properties. In particular, it may be the case that a suitable average of the speed of sound squared exceeds the so-called conformal limit, i.e.,…
We use time-evolutions of the linear perturbation equations to study the oscillations of rapidly rotating neutrons stars. Our models account for the buoyancy due to composition gradients and we study, for the first time, the nature of the…
This review is focused on tests of Einstein's theory of General Relativity with gravitational waves that are detectable by ground-based interferometers and pulsar timing experiments. Einstein's theory has been greatly constrained in the…
We study the scattering of a massless and neutral test particle in the gravitational field of a body (the string star) made of a large number of scalar states of the superstring. We consider two cases, the one in which these states are…
Neutron stars with near-Eddington observable luminosities were shown to harbor levitating atmospheres, suspended above their surface. We report a new method to simultaneously measure the mass and radius of a neutron star based on…
The spectrum of frequencies and characteristic times that compose the ringdown phase of gravitational waves emitted by neutron stars carries information about the matter content (the equation of state) and the underlying theory of gravity.…
Many thermonuclear X-ray bursts exhibit brightness oscillations. The brightness oscillations are thought to be due to the combined effects of non-uniform nuclear burning and rotation of the neutron star. The waveforms of the oscillations…
We investigate how matter density affects neutrino oscillations by considering a mass-varying neutrino scenario where the neutrino mass depends on a scalar field. This scalar field is non-minimally coupled to the Gauss-Bonnet (GB)…