Quadrupole effects on the motion of extended bodies in Schwarzschild spacetime

The motion of an extended body up to the quadrupolar structure is studied in the Schwarzschild background following Dixon's model and within certain restrictions (constant frame components for the spin and the quadrupole tensor, center of mass moving along a circular orbit, etc.). We find a number of interesting situations in which deviations from the geodesic motion, due to the internal structure of the particle, can originate measurable effects. However, the standard clock-effect for a pair co/counter-rotating bodies spinning up/down is not modified by the quadrupolar structure of the particle.Comment: 9 pages, latex iopart class document, no figures. Note that the second term in the rhs of Eq. (1.2) was misprinted in the published version of the paper [Classical and Quantum Gravity, Vol. 25, 035005 (2008)]. The results are but correc

Measuring Electromagnetic Fields in Rotating Frames

We review the problem of transforming electromagnetic fields between inertial and rotating reference frames. We compare the method of straightforward tensor coordinate transformations adopted by Schiff in his well-known paper of 1939 with the method of Orthogonal Tetrads (OT) that was applied to this problem in 1964 by Irvine. Although both methods are mathematically rigorous, the transformed fields have different forms depending on the method adopted. We emphasize that the OT method is expected to predict the fields that would actually be measured by an observer in a rotating frame of reference. We briefly discuss existing experimental evidence that supports the OT approach, but point out that there appears to be little awareness in the physics community of this problem or its resolution. We use both methods to transform the electrostatic and magnetic fields generated by rotating charged spherical shells from an inertial into a co-rotating system. We also briefly describe how such an arrangement of shells could be used to measure rotation relative to the fixed stars

Search for gravitational wave bursts by wavelet packet decomposition: The detection algorithm

We present a novel method based on wavelet packet transformation for detection of gravitational wave (gw) bursts embedded in additive Gaussian noise. The method exploits a wavelet packet decomposition of observed data and performs detection of bursts at multiple time-frequency resolutions by the extreme value statistics. We discuss the performances of detection algorithms (efficiency and robustness) in the general framework of hypothesis testing. In particular, we compare the performances of wavelet packet (WP), matched filter (MF), and power filter (PF) algorithms by means of a complete Monte Carlo simulation of the output of a gw detector, with the detection efficiencies of MF and PF playing the role of upper and lower bounds, respectively. Moreover, the performances of impulsive filter (IF) algorithm, widely used in the data analysis of resonant gw detectors, have been investigated. Results we get by injecting chirplet signals confirm the expected performances in terms of efficiency and robustness. To illustrate the application of the new method to real data, we analyzed a few data sets of the resonant gw detector AURIGA

Gravito-magnetic resonance in the field of a gravitational wave

Using the construction of the Fermi frame, the field of a gravitational wave can be described in terms of gravito-electromagnetic fields that are transverse to the propagation direction and orthogonal to each other. In particular, the gravito-magnetic field acts on spinning particles and we show that, due to the action of the gravitational wave field, a new phenomenon, that we call gravito-magnetic resonance, may appear. We give both a classical and a quantum description of this phenomenon and suggest that it can be used as the basis for a new type of gravitational wave detectors. Our results highlight the effectiveness of collective spin excitations, e.g. spin waves in magnetized materials, in detecting high frequency gravitational waves. Here we suggest that, when gravitational waves induce a precession of the electron spin, power is released in the ferromagnetic resonant mode endowed with quadrupole symmetry of a magnetized sphere. This offers a possible path to the detection of the gravito-magnetic effects of a gravitational wave.Comment: 6 page

Light scattering by radiation fields: the optical medium analogy

The optical medium analogy of a radiation field generated by either an exact gravitational plane wave or an exact electromagnetic wave in the framework of general relativity is developed. The equivalent medium of the associated background field is inhomogeneous and anisotropic in the former case, whereas it is inhomogeneous but isotropic in the latter. The features of light scattering are investigated by assuming the interaction region to be sandwiched between two flat spacetime regions, where light rays propagate along straight lines. Standard tools of ordinary wave optics are used to study the deflection of photon paths due to the interaction with the radiation fields, allowing for a comparison between the optical properties of the equivalent media associated with the different background fields.Comment: 6 pages, 4 figures; published versio