Imprints of gravitational-wave polarizations on projected tidal tensor in three dimensions

Fuente: arXiv
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Main Authors: Mikura, Yusuke, Okumura, Teppei, Sasaki, Misao
Format: Preprint
Published: 2025
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author Mikura, Yusuke
Okumura, Teppei
Sasaki, Misao
author_facet Mikura, Yusuke
Okumura, Teppei
Sasaki, Misao
contents Gravitational waves (GWs) distort galaxy shapes through the tidal effect, offering a novel avenue to probe the nature of gravity. In this paper, we investigate how extra GW polarizations beyond those predicted by general relativity imprint observable signatures on galaxy shapes. Since galaxy shapes are measured as two-dimensional images projected onto the celestial sphere, we present three-dimensional statistical quantities of the projected tidal tensor sourced by the tensor perturbation. We show that the presence of extra polarization modes modifies both the amplitude and angular dependence of the correlation functions. Furthermore, we identify a distinct observational channel for probing parity violation in helicity-two and helicity-one modes. In particular, we show that if they propagate at different speeds, galaxy surveys can disentangle the source of parity violation. Our findings establish a theoretical framework for using upcoming large-scale galaxy surveys to test modified gravity theories through the polarization content of GWs.
format Preprint
id arxiv_https___arxiv_org_abs_2507_23302
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Imprints of gravitational-wave polarizations on projected tidal tensor in three dimensions
Mikura, Yusuke
Okumura, Teppei
Sasaki, Misao
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Gravitational waves (GWs) distort galaxy shapes through the tidal effect, offering a novel avenue to probe the nature of gravity. In this paper, we investigate how extra GW polarizations beyond those predicted by general relativity imprint observable signatures on galaxy shapes. Since galaxy shapes are measured as two-dimensional images projected onto the celestial sphere, we present three-dimensional statistical quantities of the projected tidal tensor sourced by the tensor perturbation. We show that the presence of extra polarization modes modifies both the amplitude and angular dependence of the correlation functions. Furthermore, we identify a distinct observational channel for probing parity violation in helicity-two and helicity-one modes. In particular, we show that if they propagate at different speeds, galaxy surveys can disentangle the source of parity violation. Our findings establish a theoretical framework for using upcoming large-scale galaxy surveys to test modified gravity theories through the polarization content of GWs.
title Imprints of gravitational-wave polarizations on projected tidal tensor in three dimensions
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2507.23302