The gravitational Faraday and its dual spin-Hall effects of light arise in space-times of nonzero angular momentum. These effects were studied in stationary, asymptotically flat space-times. Here we study these effects in arbitrary, nonstationary, asymptotically flat space-times. These effects arise from the interaction between light polarization and space-time angular momentum. As a result of such interaction, the phase velocity of left- and right-handed circularly polarized light becomes different, that results in the gravitational Faraday effect. This difference implies different dynamics of these components, that begin to propagate along different paths—the gravitational spin-Hall effect of light. Due to this effect, the gravitational field splits a multicomponent beam of unpolarized light and produces polarized gravitational rainbow. The component separation is an accumulative effect observed in long range asymptotics. To study this effect, we construct uniform eikonal expansion and derive dynamical equation describing this effect. To analyze the dynamical equation, we present it in the local space and time decomposition form. The spatial part of the equation presented in the related optical metric is analogous to the dynamical equation of a charged particle moving in magnetic field under the influence of the Coriolis force.

Observations of gravitational waves from compact binary mergers have enabled unique tests of general relativity in the dynamical and non-linear regimes. One of the most important such tests is constraints on the post-Newtonian (PN) corrections to the phase of the gravitational wave signal. The values of the PN coefficients can be calculated within standard general relativity, and these values are different in many alternate theories of gravity. It is clearly of great interest to constrain the deviations based on gravitational wave observations. In the majority of such tests which have been carried out, and which yield by far the most stringent constraints, it is common to vary these PN coefficients individually. While this might in principle be useful for detecting certain deviations from standard general relativity, it is a serious limitation. For example, we would expect alternate theories of gravity to generically have additional parameters. The corrections to the PN coefficients would be expected to depend on these additional non-GR parameters, whence, we expect that the various PN coefficients to be highly correlated. We present an alternate analysis here using data from the binary neutron star coalescence GW170817. Our analysis uses an appropriate linear combination of non-GR parameters that represent absolute deviations from the corresponding post-Newtonian inspiral coefficients in the TaylorF2 approximant phase. These combinations represent uncorrelated non-GR parameters which correspond to principal directions of their covariance matrix in the parameter subspace. Our results illustrate good agreement with GR. In particular, the integral non-GR phase is $$\Psi _{{\tiny int-non-GR}} = 0.0447\pm 25.3000$$Ψ i n t - n o n - G R = 0.0447 ± 25.3000 and the deviation from GR percentile is $$p^{{\tiny Dev-GR}}_{n}=25.85\%$$p n D e v - G R = 25.85 % .

Matched filtering is a traditional method used to search a data stream for signals. If the source (and hence its $n$ parameters) are unknown, many filters must be employed. These form a grid in the $n$-dimensional parameter space, known as a template bank. It is often convenient to construct these grids as lattices. The simplest of these, ${\mathbb{Z}}^n$, is used in both continuous gravitational-wave and gamma-ray pulsar searches; we wanted to investigate how much might be gained by replacing it with the more elaborate $A_n^{*}$ lattice. To determine this, we calculate the distribution of the mismatch function, both in the traditional quadratic approximation and with the recently proposed spherical ansatz. The fraction of signals which are lost is determined by the even moments of this distribution, which we find. Many of these quantities have a simple and well-defined $n\to \infty$ limit, which often gives an accurate estimate even for small $n$. Our main conclusions are the following: (i) a fairly effective template-based search can be constructed at mismatch values that are shockingly high in the quadratic approximation; (ii) the minor advantage offered by an $A_n^{*}$ template bank (compared to ${\mathbb{Z}}^n$) at small template separation becomes even less significant for large template spacings. In most cases, the gain from employing an $A_n^{*}$ lattice is not enough to justify the increase in complexity.

In this paper we discuss propagation of the weak high-frequency gravitational waves in a curved spacetime background. We develop a so-called spinoptics approximation which takes into account interaction of the spin of the field with the curvature of the background metric. This is achieved by modifying the standard geometric optics approximation by including the helicity sensitive terms of the order 1/ω in the eikonal equation. The novelty of the approach developed in this paper is that instead of study of the high-frequency expansion of the equations for the gravitational field perturbations we construct the effective action for the gravitational spinoptics. The gravitational spinoptics equations derived by variation of the effective action correctly reproduce the earlier obtained results. However, the proposed effective action approach is technically more simple and transparent. It allows one to reduce the study of the high-frequency gravitational waves to study classical dynamics of massless particles with internal discrete degree of freedom (helicity). The formalism is covariant and it can be applied for arbitrary vacuum space-time background.

A gravitational field can cause a rotation of the polarization plane of light. This phenomenon is known as the gravitational Faraday effect. It arises due to different spin-orbit interactions of left- and right-handed circularly polarized components of light. Such an interaction also causes transverse displacement in the light trajectory, in opposite directions for each component. This phenomenon is known as the gravitational spin-Hall effect of light. We study these effects in a local inertial frame in arbitrary vacuum spacetime and show that they are observer dependent and arise due to interaction of light polarization with a local gravitomagnetic field measured by the observer. Thus, to address the effects to a gravitational field alone, one has to consider zero angular momentum observers. Published by the American Physical Society 2024

We study the Gregory-Laflamme instability of 5D compactified, electrically charged black strings. We consider static, linear perturbations of these solutions and derive master equation for these perturbations. Using numerical analysis we search for the threshold unstable modes and derive the critical wave-length. The results are illustrated in the black string mass v.s. electric charge phase diagram. Similar diagram is constructed using global thermodynamic equilibrium argument applied to the charged string and 5D electrically charged black hole. The results derived illustrate that electric charge makes the black string less stable.Comment: 8 pages, 2 figures; Some minor changes in the text. Added reference