相关论文: Stellar Pulsations in Beyond Horndeski Gravity The…
Some tests of gravity theories - periastron shift, geodetic precession, change in mean motion and gravitational redshift - are applied in solar and stellar systems to constrain the cosmological constant. We thus consider a length scale…
The lack of rotating black holes, typically found in nature, hinders testing modified gravity from astrophysical observations. We present the axially symmetric counterpart of an existing spherical hairy black hole in Horndeski gravity…
In scalar-tensor Horndeski theories, nonsingular cosmological models - bounce and genesis - are problematic because of potential ghost and/or gradient instabilities. One way to get around this obstacle is to send the effective Planck mass…
In Horndeski theories containing a scalar coupling with the Gauss-Bonnet (GB) curvature invariant $R_{\rm GB}^2$, we study the existence and linear stability of neutron star (NS) solutions on a static and spherically symmetric background.…
We study the oscillations of neutron and strange stars in $R^2$ gravity. More precisely the nonradial $f$-modes are examined and the differences with pure general relativity are investigated. Using these results we build several…
The motivations for investigating a theory of gravitation based on a concept of "ether" are discussed-- a crucial point is the existence of an alternative interpretation of special relativity, named the Lorentz-Poincar\'e ether theory. 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…
In general the speed of Gravitational Waves (GWs) in Scalar-Tensor modifications of Einstein's gravity is different from the speed of Light. Nevertheless, it has been measured that their speeds are nearly the same. For the most general…
Pulsars in close binary orbit around another neutron star or a massive white dwarf make ideal laboratories for testing the predictions of gravitational radiation and self-gravitational effects. We report new timing measurements of the…
One century after its formulation, Einstein's general relativity has made remarkable predictions and turned out to be compatible with all experimental tests. Most of these tests probe the theory in the weak-field regime, and there are…
In this work we present a brief discussion about modified and extended cosmological models using current observational tests. We show that according to these astrophysical samples based in late universe measurements, theories like $f(R)$…
This work investigates alternative theories of gravity, the solutions to their field equations and the constraints that can be imposed upon them from observation and experiment. Specifically, we consider the cosmologies and spherically…
Most of the information on our cosmos stems from either late-time observations or the imprint of early-time inhomogeneities on the cosmic microwave background. We explore to what extent early modifications of gravity, which become…
The opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. It is hoped that within the next decade pulsar timing will…
We determine the conditions for which the constraints from lunar laser ranging on the time evolution of the local gravitational constant can be extrapolated to impose constraints on the time evolution of the cosmological gravitational…
Pulsars are the most stable macroscopic clocks found in nature. Spinning with periods as short as a few milliseconds, their stability can supersede that of the best atomic clocks on Earth over timescales of a few years. Stable clocks are…
Stars closely approaching the massive black hole in the center of the Galaxy provide a unique opportunity to probe post-Newtonian physics in a yet unexplored regime of celestial mechanics. Recent advances in infrared stellar spectroscopy…
During the course of an ongoing CCD monitoring program to investigate low-level light variations in subdwarf B (sdB) stars, we have serendipitously discovered a new class of low amplitude, multimode sdB pulsators with periods of the order…
This work is devoted to the construction of slowly rotating neutron stars in the framework of the nonminimal derivative coupling sector of Horndeski theory. We match the large radius expansion of spherically symmetric solutions with…
Future space-based tests of relativistic gravitation-laser ranging to Phobos, accelerometers in orbit, and optical networks surrounding Earth-will constrain the theory of gravity with unprecedented precision by testing the inverse-square…