Related papers: Angular momentum sensitivities in scalar-tensor th…
We investigate neutron stars in scalar-tensor theories. We examine their secular stability against spherically symmetric perturbations by use of a turning point method. For some choices of the coupling function contained in the theories,…
We discuss some of the issues which we encounter when we try to invoke the scalar-tensor theories of gravitation as a theoretical basis of quintessence. One of the advantages of appealing to these theories is that they allow us to implement…
There has been a recent revival in understanding the spontaneous scalarization phenomenon in scalar-tensor gravity as a phase transition. Using the tools of the Landau theory, we now know that first-order transitions where scalarization…
Scalar-tensor~(ST) theories of gravity are natural phenomenological extensions to general relativity. Although these theories are severely constrained both by solar system experiments and by binary pulsar observations, a large set of ST…
Scalar-tensor gravity models are among the prime candidates to explain cosmic acceleration, and compact stars provide unique laboratories for testing such theories. Predictions of scalar-tensor gravity in compact stars can be examined…
We address neutron stars and black holes in alternative gravities, after recalling their basic properties in General Relativity. Among the plethora of interesting alternative gravities we here focus on an interesting set of scalar-tensor…
Detection of the characteristic spectrum of pulsating neutron stars can be a powerful tool not only to probe the nuclear equation of state, but also to test modifications to general relativity. However, the shift in the oscillation spectrum…
We search for viable f(R) theories of gravity, making use of the equivalence between such theories and scalar-tensor gravity. We find that models can be made consistent with solar system constraints either by giving the scalar a high mass…
We consider alternative theories of gravity with a direct coupling between matter and the Ricci scalar We study the relation between these theories and ordinary scalar-tensor gravity, or scalar-tensor theories which include non-standard…
Ferromagnetic spin ordering can take place in neutron stars. This phase transition alters the neutron star equation of state. Here, applying the scalar-tensor theories of gravity, we investigate the structure of neutron stars which are in…
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…
The masses and radii of neutron stars are discussed in general relativity and scalar-tensor theory of gravity and the differences are compared with the current uncertainties stemming from the nuclear equation of state in the relativistic…
Differentially rotating scalarized neutron stars, mimickers of binary merger remnants, can possess an enormous angular momentum larger than what could possibly be sustained in a neutron star in general relativity by about one order of…
We show that, as a result of non-linear self-interactions, it is feasible, at least in light of the bounds coming from terrestrial tests of gravity, measurements of the Casimir force and those constraints imposed by the physics of compact…
This talk reviews the constraints imposed by binary-pulsar data on gravity theories, and notably on "scalar-tensor" theories which are the most natural alternatives to general relativity. Because neutron stars have a strong gravitational…
Neutron stars (NSs) in scalar-tensor (ST) theories of gravitation can acquire scalar charges and generate distinct spacetimes from those in General Relativity (GR) through the celebrated phenomenon of spontaneous scalarization. Taking on an…
Pulsar-timing has become a celebrated tool for probing modifications to General Relativity in the strong-field surroundings of neutron stars. Here we investigate whether scalar-tensor theories that incorporate a nonminimally coupled scalar…
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…
Scalar-tensor gravity is the simplest and best understood modification of general relativity, consisting of a real scalar field coupled directly to the Ricci scalar curvature. Models of this type have self-accelerating solutions. In an…
We study static, spherically symmetric neutron stars in a class of scalar-tensor theories with non-canonical kinetic terms (K-essence) obeying all causality and hyperbolicity conditions. These models have non-trivial dynamics that lead to a…