Related papers: Constraints on fourth order gravity from binary pu…
The orbital period loss of the compact binary systems is the first indirect evidence of gravitational waves which agrees well with Einstein's general theory of relativity to a very good accuracy. However, there is less than one percent…
We analyze the observational constraints on the effective Brans-Dicke parameter and on the temporal variation of the effective gravitational constant within the context of the oscillating G model, a cosmological model based on a massive…
This article provides the details on the technical derivation of the gravitational waveform and total gravitational-wave energy flux of non-spinning compact binary systems to the 4PN (fourth post-Newtonian) order beyond the Einstein…
We present new cosmological parameter constraints for general Horndeski scalar-tensor theories, using CMB, redshift space distortion, matter power spectrum and BAO measurements from the Planck, SDSS/BOSS and 6dF surveys. We focus on…
Scalar-tensor gravity represents a natural extension of general relativity. This paper investigates a conformal scalar-tensor gravity, the environmentally dependent dilaton model, and identifies regions of its parameter space potentially…
The post-Newtonian gravitoelectric secular rate of the mean anomaly M is worked out for a two-body system in the framework of the General Theory of Relativity. The possibility of using such an effect, which is different from the well known…
Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the…
General relativity is a fully conservative theory, but there exist other possible metric theories of gravity. We consider non-conservative ones with a parameterized post-Newtonian (PPN) parameter, $\zeta_2$. A non-zero $\zeta_2$ induces a…
Alternative theories of gravity not only modify the polarization contents of the gravitational wave, but also affect the motions of the stars and the energy radiated away via the gravitational radiation. These aspects leave imprints in the…
The evidence of gravitational wave was first indirectly confirmed by the orbital period loss of Hulse-Taylor binary system which agrees well with the Einstein's general relativistic prediction. The perihelion precession of planets,…
The timing of binary pulsars allows us to place some of the tightest constraints on modified theories of gravity. Perhaps some of the most interesting and well-motivated extensions to General Relativity are scalar-tensor theories, in which…
We investigate the new observational constraints on $f(T)$ gravity that arise from the effects of primordial gravitational waves (GWs) on the cosmic microwave background (CMB) anisotropies and the BB spectrum. We first show that on the GWs…
Future observations of the large-scale structure have the potential to investigate cosmological models with a high degree of complexity, including the properties of gravity on large scales, the presence of a complicated dark energy…
Amplitude and phase of the gravitational waveform from compact binary systems can be decomposed in terms of their mass- and current-type multipole moments. In a modified theory of gravity, one or more of these multipole moments could…
In this paper we place new constraints on a f(R) modified gravity model recently proposed by Hu and Sawicki. After checking that the Hu and Sawicki model produces a viable cosmology, i.e. a matter dominated epoch followed by a late-time…
Alternative theories of gravity may serve to overcame several shortcomings of the standard cosmological model but, in their weak field limit, General Relativity must be recovered so as to match the tight constraints at the Solar System…
Binary pulsars are excellent laboratories to test the building blocks of Einstein's theory of General Relativity. One of these is Lorentz symmetry which states that physical phenomena appear the same for all inertially moving observers. We…
We study the constraints that spatial topology may place on the parameters of models that account for the accelerated expansion of the universe via infrared modifications to general relativity, namely the Dvali-Gabadadze-Porrati braneworld…
Recently, gravitational microlensing has been investigated in the framework of the weak field limit of fourth order gravity theory. However, solar system data (i.e. planetary periods and light bending) can be used to put strong constraints…
Recent astrophysical observations have provided strong evidence that the present expansion of the universe is accelerating, powered by the energy density associated with a cosmological term. Assuming the latter to be not simply a constant…