Wave Optics Effects from Gravitational Wave Propagation Through Dark Matter Halos
Abstract
Gravitational wave (GW) propagation is usually studied under the geometric optics approximation. However, when GWs propagate through structures of sizes similar to their wavelength, this approximation breaks down. To study this situation, we present a scheme for numerically evolving linearised plane GWs through stationary, spherical astrophysical structures in both weak and strong gravity regimes. Our simulations evolve the full Einstein equations (with all 10 components) for Gaussian, NFW and Burkert potentials. Our simulations show that the scattering of the GWs depends not only on the mass of the lens but also strongly on the gravitational potential distribution of the lens. Among our most important results, we find that the GWs do not propagate along null geodesics when propagating through the Gaussian density, neither in the strong nor weak gravity setting. Another significant finding is that in the strong gravity case of the Burkert potential, the convexity of the wave is flipped when leaving the structure. We compare our results with the linearized scalar wave predictions and find that the difference between these and the exact GW modes are of order one when the wave is inside the central potential. However, the difference reduces to only a few percent when the wave has passed through the structure. Although these effects are small, future GW detectors and Pulsar Timing Arrays (PTAs) could be sensitive to these signals which could thus potentially help in constraining the structure of dark matter spikes or halos.
Related
- Probing Dark Matter Substructure with Wave-Optics Distortions of Strongly Lensed LISA Gravitational Waves
- Wave-Optics Imprints of Warm Dark Matter Subhalos with Prompt Cusps on Strongly Lensed Gravitational Waves
- Close Pulsar Pairs See Dark Matter Substructure through the Gravitational-Wave Background
- Testing Charged Black Holes Embedded in Anisotropic Matter and Surrounded by Plasma through Gravitational Lensing: Bounds from the Sloan Lens ACS Survey
- Testing the Isothermal Jeans Model for Self-interacting Dark Matter Halos in the Collapse Phase
BibTeX
@misc{shanmugaraj2026wave,
title = {{Wave Optics Effects from Gravitational Wave Propagation Through Dark Matter Halos}},
author = {Annamalai P. Shanmugaraj and Roland Haas and Erik Schnetter and Sofie Marie Koksbang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.30149},
eprint = {2606.30149},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.30149},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Wave Optics Effects from Gravitational Wave Propagation Through Dark Matter Halos
AU - Annamalai P. Shanmugaraj
AU - Roland Haas
AU - Erik Schnetter
AU - Sofie Marie Koksbang
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2606.30149
UR - https://arxiv.org/abs/2606.30149
AB - Gravitational wave (GW) propagation is usually studied under the geometric optics approximation. However, when GWs propagate through structures of sizes similar to their wavelength, this approximation breaks down. To study this situation, we present a scheme for numerically evolving linearised plane GWs through stationary, spherical astrophysical structures in both weak and strong gravity regimes. Our simulations evolve the full Einstein equations (with all 10 components) for Gaussian, NFW and Burkert potentials. Our simulations show that the scattering of the GWs depends not only on the mass of the lens but also strongly on the gravitational potential distribution of the lens. Among our most important results, we find that the GWs do not propagate along null geodesics when propagating through the Gaussian density, neither in the strong nor weak gravity setting. Another significant finding is that in the strong gravity case of the Burkert potential, the convexity of the wave is flipped when leaving the structure. We compare our results with the linearized scalar wave predictions and find that the difference between these and the exact GW modes are of order one when the wave is inside the central potential. However, the difference reduces to only a few percent when the wave has passed through the structure. Although these effects are small, future GW detectors and Pulsar Timing Arrays (PTAs) could be sensitive to these signals which could thus potentially help in constraining the structure of dark matter spikes or halos.
ER -