arXiv subjects

Stefan Palenta

Publications and source records attributed to Stefan Palenta.

8 recordsLinked to original sources

arXiv2023

Response of an Interferometer Mounted on an Elastic Square Plate to Gravitational Waves

Laser-interferometric gravitational wave detectors are commonly modeled as being at rest in transverse-traceless coordinates (and thus geodesic). In this paper, we analyze what happens if the interferometer is mounted on a material that can undergo elastic oscillations caused by the gravitational wave. We thus compute the response of a two-dimensional elastic material to linearized gravitational radiation and compute the resulting response of a laser interferometer, mounted on such a plate.

gr-qc↗

arXiv2023

Relativistic Theory of Elastic Bodies in the Presence of Gravitational Waves

The equations of motion governing small elastic oscillations of materials, induced by gravitational waves, are derived from the general framework of Carter and Quintana. In transverse-traceless gauge, no bulk forces are present, and the gravitational wave is found to act as an effective surface traction. For thin rods, an equivalent description is given, in which there is no surface traction, but a bulk acceleration, which is related to the Riemann curvature of the gravitational wave. The resulting equations are compared to those of the Synge-Bennoun elasticity theory.

gr-qc↗

arXiv2021

The Resolution of Ambiguities in Light Perturbation by Gravitational Waves

Some previously published expressions for the perturbation of light by gravitational waves exhibit pathological behaviour in the limit of parallel propagation. We show that this is caused by similarly pathological initial or boundary data and can thus be remedied by implementing better-behaved initial conditions.

gr-qc↗

arXiv2021

The Electromagnetic Field in Gravitational Wave Interferometers

We analyse the response of laser interferometric gravitational wave detectors using the full Maxwell equations in curved spacetime in the presence of weak gravitational waves. Existence and uniqueness of solutions is ensured by setting up a suitable boundary value problem. This puts on solid ground previous approximate calculations. We find consistency with previous results obtained from eikonal expansions at the level of accuracy accessible to current gravitational wave detectors.

gr-qc↗

arXiv2018

A continuous Riemann-Hilbert problem for colliding plane gravitational waves

We present the foundations of a new solution technique for the characteristic initial value problem (IVP) of colliding plane gravitational waves. It has extensive similarities to the approach of Alekseev and Griffiths in 2001, but we use an inverse scattering method with a Riemann-Hilbert problem (RHP), which allows for a transformation to a continuous RHP with a solution given in terms of integral equations for non-singular functions. Ambiguities in this procedure lead to the construction of a family of spacetimes containing the solution to the IVP. Therefore the described technique also serves as an interesting solution generating method. The procedure is exemplified by extending the Szekeres class of colliding wave spacetimes with 2 additional real parameters. The obtained solution seems to feature a limiting case of a new type of impulsive waves, which are circularly polarised.

gr-qc↗

arXiv2016

Gyromagnetic factor of rotating disks of electrically charged dust in general relativity

We calculated the dimensionless gyromagnetic ratio ("$g$-factor") of self-gravitating, uniformly rotating disks of dust with a constant specific charge $ε$. These disk solutions to the Einstein-Maxwell equations depend on $ε$ and a "relativity parameter" $γ$ ($0<γ\le 1$) up to a scaling parameter. Accordingly, the $g$-factor is a function $g=g(γ,ε)$. The Newtonian limit is characterized by $γ\ll 1$, whereas $γ\to 1$ leads to a black-hole limit. The $g$-factor, for all $ε$, approaches the values $g=1$ as $γ\to 0$ and $g=2$ as $γ\to 1$.

gr-qc↗

arXiv2015

On the black hole limit of rotating discs of charged dust

Investigating the rigidly rotating disc of dust with constant specific charge, we find that it leads to an extreme Kerr-Newman black hole in the ultra-relativistic limit. A necessary and sufficient condition for a black hole limit is, that the electric potential in the co-rotating frame is constant on the disc. In that case certain other relations follow. These relations are reviewed with a highly accurate post-Newtonian expansion. Remarkably it is possible to survey the leading order behaviour close to the black hole limit with the post-Newtonian expansion. We find that the disc solution close to that limit can be approximated very well by a "hyper\-extreme" Kerr-Newman solution with the same gravitational mass, angular momentum and charge.

gr-qc↗

arXiv2013

Post-Newtonian expansion of a rigidly rotating disc of dust with a constant specific charge

We present an algorithm for obtaining the post-Newtonian expansion of the asymptotically flat solution to the Einstein-Maxwell equations describing a rigidly rotating disc of dust with a constant specific charge. Explicit analytic expressions are calculated up to the eighth order. The results are used for a physical discussion of the extreme relativistic limiting cases. We identify strong evidence for a transition to an extreme Kerr-Newman black hole.

gr-qc↗