Related papers: Ultra long lived quasinormal modes of neutron star…
The frequencies of quasi-periodic oscillations around neutron stars are believed to be related to characteristic frequencies in the gravitational fields of the compact objects. In different variability models, these include the Keplerian,…
Neutron star interiors are a fantastic laboratory for high density physics in extreme environments. Probing this system with standard electromagnetic observations is, however, a challenging endeavour, as the radiation tends to be scattered…
Binary neutron star mergers, which can lead to less massive black holes relative to other known astrophysical channels, have the potential to probe modifications to general relativity that arise at smaller curvature scales compared to more…
Scalar-tensor theories of gravity are extensions of General Relativity (GR) including an extra, nonminimally coupled scalar degree of freedom. A wide class of these theories, albeit indistinguishable from GR in the weak field regime,…
Among the possible extensions of General Relativity that have been put forward in order to address some long standing issues in our understanding of the Universe, Scalar-Tensor Theories have received a lot of attention for their simplicity.…
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.,…
An alternative theory of gravity has recently been proposed by Bekenstein, named Tensor-Vector-Scalar (TeVeS) theory, which can explain many galactic and cosmological observations without the need for dark matter. Whilst this theory passes…
Scalar-tensor theories allow for a rich spectrum of quasinormal modes of neutron stars. The presence of the scalar field allows for polar monopole and dipole radiation, as well as for additional higher multipole modes led by the scalar…
Modified theories of gravity that offer viable models for dark energy often rely on mechanisms that screen their effects in high density environments. From this perspective, it would appear that, once solar system constraints are satisfied,…
We present a full 3D numerical evolution code to study neutron stars in massive-scalar-tensor theories. The code is embedded in the Einstein Toolkit framework and its implementation constitutes a modified version of the…
We derive the perturbation equations for relativistic stars in scalar-tensor theories of gravity and study the corresponding oscillation spectrum. We show that the frequency of the emitted gravitational waves is shifted proportionally to…
Gravitational redshifts of neutron stars have a theoretical upper limit of z=0.62. Also, it is generally believed that neutron stars have magnetic fields on the order of ten to the twelfth to ten to the thirteenth G. A previously predicted…
The effects that the structure of a neutron star would have on the gravitational emission of a binary system are studied in a perturbative regime, and in the frequency domain. Assuming that a neutron star is perturbed by a point mass moving…
Neutron stars are known to host extremely powerful magnetic fields. Among other effects, one of the consequences of harbouring such fields is the deformation of the neutron star structure, leading, together with rotation, to the emission of…
The spectrum of the quasinormal modes of the gravitational waves emitted during the ringdown phase following the merger of two black holes is of primary importance in gravitational astronomy. However, the spectrum is extremely sensitive to…
We study the orbital and epicyclic frequencies of particles orbiting around rapidly rotating neutron stars and strange stars in a particular scalar-tensor theory of gravity. We find very large deviations of these frequencies, when compared…
We present a scenario of formation of strange stars due to spin-down of {\it rapidly rotating} neutron stars left after supernova explosions . By assuming a process where the total baryon mass is conserved but the angular momentum is lost…
Gravitational waves are tiny disturbances in space-time and are a fundamental, although not yet directly confirmed, prediction of General Relativity. Rapidly rotating neutron stars are one of the possible sources of gravitational radiation…
Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernov\ae{}, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within…
We study neutron star configurations in a simple shift-symmetric subfamily of degenerate higher-order scalar-tensor (DHOST) theories, whose deviations from General Relativity (GR) are characterized by a single parameter. We compute the…