arXiv subjects

Christian Corda

Publications and source records attributed to Christian Corda.

105 records · Page 6Linked to original sources

arXiv2008

On the longitudinal response function of interferometers for massive gravitational waves from a bimetric theory of gravity

Recently, some papers in the literature have shown that, from a bimetric theory of gravity, it is possible to produce massive gravitational waves which generate a longitudinal component in a particular polarization of the wave. After a review of previous works, in this paper the longitudinal response function of interferometers for this particular polarization of the wave is computed in two different gauges, showing the gauge invariance, and in its full frequency dependence, with specific application to the Virgo and LIGO interferometers.

gr-qc↗

arXiv2008

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

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.

gr-qc↗

arXiv2008

"Magnetic" components of gravitational waves and response functions of interferometers

Recently, arising from an enlighting analysis of Baskaran and Grishchuk in Class. Quant. Grav. 21, 4041-4061 (2004), some papers in the literature have shown the presence and importance of the so-called "magnetic" components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions of interferometers for GWs propagating from arbitrary directions. In Int. Journ. Mod. Phys. A 22, 13, 2361-2381 (2007) and Int. J. Mod. Phys. D 16, 9, 1497-1517 (2007) accurate response functions for the Virgo and LIGO interferometers have been analysed. However, some results which have been shown in Int. Journ. Mod. Phys. A 22, 13, 2361-2381 (2007) look in contrast with the results which have been shown in Int. J. Mod. Phys. D 16, 9, 1497-1517 (2007). In fact, in Int. Journ. Mod. Phys. A 22, 13, 2361-2381 (2007) it was claimed that the "magnetic" component of GWs could, in principle, extend the frequency range of Earth based interferometers, while in Int. J. Mod. Phys. D 16, 9, 1497-1517 (2007) such a possibility has been banned. This contrast has been partially solved in the Proceedings of the XLIInd Rencontres de Moriond, Gravitational Waves and Experimental Gravity, La Thuile, Val d'Aosta Italy (March 12-18 2007). The aim of this review paper is to re-analyse all the framework of the "magnetic" components of GWs with the goal of solving the mentioned contrast in definitive way. Accurate response funtions for the Virgo and LIGO interferometers will be also re-discussed in detail.

gr-qc↗

arXiv2008

An oscillating Universe from the linearized R^{2} theory of gravity

An oscillating Universe which arises from the linearized R^{2} 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.

astro-ph↗

arXiv2008

A non-geodesic motion in the R^-1 theory of gravity tuned with observations

In the general picture of high order theories of gravity, recently, the R^-1 theory has been analyzed in two different frameworks. In this letter a third context is added, considering an explicit coupling between the R^-1 function of the Ricci scalar and the matter Lagrangian. The result is a non-geodesic motion of test particles which, in principle, could be connected with Dark Matter and Pioneer anomaly problems.

astro-ph↗

arXiv2007

Massive gravitational waves from the R^2 theory of gravity: production and response of interferometers

We show that from the R^{2} high order gravity theory it is possible to produce, in the linearized approch, particles which can be seen like massive modes of gravitational waves (GWs). The presence of the mass generates a longitudinal force in addition of the transverse one which is proper of the massless gravitational waves and the response an interferometer to the effect is computed. This could be, in principle, important to discriminate among the gravity theories. The presence of the mass could also have important applications in cosmology because the fact that gravitational waves can have mass could give a contribution to the dark matter of the Universe.

gr-qc↗

arXiv2007

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.

astro-ph↗

arXiv2007

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.

astro-ph↗

arXiv2007

Analysis of the transverse effect of Einstein's gravitational waves

The investigation of the transverse effect of gravitational waves (GWs) could constitute a further tool to discriminate among several relativistic theories of gravity on the ground. After a review of the TT gauge, the transverse effect of GWs arising by standard general relativity (called Einstein's GWs in this paper) is reanalized with a different choice of coordinates. In the chosen gauge test masses have an apparent motion in the direction of propagation of the wave, while in the transverse direction they appear at rest. Of course, this is only a gauge artefact. In fact, from careful investigation of this particular gauge, it is shown that the tidal forces associated with GWs act along the directions orthogonal to the direction of propagation of waves. In the analysis it is also shown, in a heuristic way, that the transverse effect of Einstein's GWs arises from the propagation of the waves at the speed of the light, thus only massless GWs are purely transverse. But, because the physics of gravitational waves has to be investigated by studing the tidal forces as appearing in the geodesic deviation equation and directly in a laboratory environment on Earth, an analysis of these tidal forces and of the transverse effect in the frame of the local observer is also performed. After this, for a further better understanding of the transverse effect, an example of a wave, which arises from scalar tensor gravity, with both transverse and genuinely longitudinal modes is given and discussed. In the example the connection between the longitudinal component and the velocity of the wave will be mathematical shown. At the end of this paper the review of the TT gauge is completed, recovering the gauge invariance between the presented gauge and the TT one.

gr-qc↗

arXiv2007

The Virgo - MiniGRAIL cross correlation for the detection of scalar gravitational waves

After a review of the frequency - dependent angular pattern of interferometers in the TT gauge for scalar gravitational waves (SGWs), which has been recently analysed by Capozziello and Corda, in this letter the result is used to study the cross correlation between the Virgo interferometer and the MiniGRAIL resonant sphere. It is shown that the overlap reduction function for the cross correlation bewteen Virgo and the monopole mode of MiniGRAIL is very small, but a maximum is also found in the correlation at about 2710Hz, in the range of the MiniGRAIL sensitivity

astro-ph↗

arXiv2007

Moriond 07 proceedings:"Extension of the frequency-range of interferometers for the "magnetic" components of gravitational waves?"

Recently some papers in the literature have shown the presence and importance of the so-called {}"magnetic" components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions of interferometers for GWs propagating from arbitrary directions. In this paper the response functions for the magnetic components are re-analysed in the full frequency dependence answering to the question of the title.

gr-qc↗

arXiv2007

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 literature. In this paper it is shown that, from a particular high order gravity theory known in literature, it is possible to produce, in the linearized approch, particles which can be seen like massive scalar modes of gravitational waves and the response of interferometers to this type of particles is analyzed. The presence of the mass 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. This longitudinal response function is directly connected with the function of the Ricci scalar in the particular action of this high order theory. 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.

astro-ph↗

arXiv2007

Extension of the frequency-range of interferometers for the ''magnetic'' components of gravitational waves?

Recently, with an enlighting treatment, Baskaran and Grishchuk have shown the presence and importance of the so-called ``magnetic'' components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions of interferometers for GWs propagating from arbitrary directions. In this paper the analysis of the response functions for the magnetic components is generalized in its full frequency dependence, while in the work of Baskaran and Grishchuk the response functions were computed only in the approximation of wavelength much larger than the linear dimensions of the interferometer. It is also shown that the response functions to the magnetic components grow at high frequencies, differently from the values of the response functions to the well known ordinary components that decrease at high frequencies. Thus the magnetic components could in principle become the dominant part of the signal at high frequencies. This is important for a potential detection of the signal at high frequencies and confirms that the magnetic contributions must be taken into account in the data analysis. More, the fact that the response functions of the magnetic components grow at high frequencies shows that, in principle, the frequency-range of Earth-based interferometers could extend to frequencies over 10000 Hz.

gr-qc↗

arXiv2007

The importance of the ''magnetic'' components of gravitational waves in the response functions of interferometers

With an enlighting analysis, Baskaran and Grishchuk have recently shown the presence and importance of the so-called ``magnetic'' components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions of interferometers for GWs propagating from arbitrary directions. In this paper more detailed angular and frequency dependences of the response functions for the magnetic components are given in the approximation of wavelength much larger than the linear dimensions of the interferometer, with a specific application to the parameters of the LIGO and Virgo interferometers. Our results agree with the work of Baskaran and Grishchuk in which it has been shown that the identification of ``electric'' and ``magnetic'' contributions is unambiguous in the long-wavelength approximation. At the end of this paper the angular and frequency dependences of the total response functions of the LIGO and Virgo interferometers are given. In the high-frequency regime the division on ``electric'' and ``magnetic'' components becomes ambiguous, thus the full theory of gravitational waves has to be used. Our results are consistent with the ones of Baskaran and Grishchuk in this case too.

gr-qc↗

arXiv2007

Using long-baseline interferometric gravitational waves detectors for high precision measures of the gravitational acceleration

A derivation of the optical axis lenght fluctations due by tilts of the mirrors of the Fabry-Perot cavity of long-baseline interferometers for the detection of gravitational waves in presence of the gravitational field of the earth is discussed. By comparing with the typical tilt-induced noises it is shown that this potential signal, which is considered a weak source of noise, is negligible for the first generation of gravitational waves interferometers, but, in principle, this effect could be used for high precision measures of the gravitational acceleration if advanced projects will achieve an high sensitivity. In that case the precision of the misure could be higher than the gravimeter realized by the Istituto di Metrologia ``Gustavo Colonnetti''.

gr-qc↗