C. Corda

A longitudinal component in massive gravitational waves arising from a bimetric theory of gravity

Abstract After a brief review of the work of de Paula, Miranda and Marinho on massive gravitational waves arising from a bimetric theory of gravity, in this paper it is shown that the presence of the mass generates a longitudinal component in a particular polarization of the wave. The effect of this polarization on test masses is performed using the geodesic deviation. At the end of this paper the detectability of this particular polarization is also discussed, showing that its angular dependence could, in principle, discriminate such polarization with respect to the ones of general relativity, will present or future detectors achieve a high sensitivity.

The production of matter from curvature in a particular linearized high order theory of gravity and the longitudinal response function of interferometers

The strict analogy between scalar–tensor theories of gravity and high order gravity is well known in the literature. In this paper it is shown that, from a particular high order gravity theory known in the literature, it is possible to produce, in the linearized approach, particles which can be seen like massive scalar modes of gravitational waves, and the response of interferometers to such particles is analysed. The presence of the mass generates a longitudinal force in addition of the transverse one which is appropriate to the massless gravitational waves and the response of an arm of an interferometer to this longitudinal effect in the frame of a local observer is computed. This longitudinal response function is directly connected to the function of the Ricci scalar in the particular action of this high order theory. Important consequences from a theoretical point of view could arise from this approach, because it opens up the possibility of using the signals seen from interferometers to understand which is the correct theory of gravitation.The presence of the mass could also have important applications in cosmology because of the fact that gravitational waves can have mass and could give a contribution to the dark matter of the Universe.

A solution of linearized Einstein field equations in vacuum used for the detection of the stochastic background of gravitational waves

Abstract A solution of linearized Einstein field equations in vacuum is given and discussed. First it is shown that, computing from our particular metric the linearized connections, the linearized Riemann tensor and the linearized Ricci tensor, the linearized Ricci tensor results equal to zero. Then the effect on test masses of our solution, which is a gravitational wave, is discussed. In our solution test masses have an apparent motion in the direction of propagation of the wave, while in the transverse direction they appear at rest. In this way it is possible to think that gravitational waves would be longitudinal waves, but, from careful investigation of this solution, it is shown that the tidal forces associated with gravitational waves act along the directions orthogonal to the direction of propagation of waves. The computation is first made in the long wavelengths approximation (wavelength much larger than the linear distances between test masses), then the analysis is generalized to all gravitational waves. In the last sections of this paper it is shown that the frequency dependent angular pattern of interferometers can be obtained from our solution and the total signal seen from an interferometer for the stochastic background of gravitational waves is computed.

An oscillating Universe from the linearized R 2 theory of gravity

An oscillating Universe which arises from the linearized R2 theory of gravity is discussed, showing that some observative evidences like the cosmological redshift and the Hubble law are in agreement with the model. In this context Dark Energy is seen like a pure curvature effect arising by the Ricci scalar.

Gravitational waves from the R-1 high order theory of gravity

This paper is a review of a previous research on gravitational waves from the R^-1 high order theory of gravity. It is shown that a massive scalar mode of gravitational waves from the R^-1 theory generates a longitudinal force in addition of the transverse one which is proper of the massless gravitational waves and the response of an arm of an interferometer to this longitudinal effect in the frame of a local observer is computed. Important conseguences from a theoretical point of view could arise from this approach, because it opens to the possibility of using the signals seen from interferometers to understand which is the correct theory of gravitation.

Tuning the stochastic background of gravitational waves with theory and observations

In this this paper the stochastic background of gravitational waves (SBGWs) is analyzed with the auxilium of the WMAP data. We emphasize that, in general, in previous works in the literature about the SBGWs, old COBE data were used. After this, we want to face the problem of how the SBGWs and f(R) gravity can be related, showing, vice versa, that a revealed SBGWs could be a powerly probe for a given theory of gravity. In this way, it will also be shown that the conformal treatment of SBGWs can be used to parametrize in a natural way f(R) theories.