On the Gauge Invariance of Secondary Gravitational Waves

Fuente: arXiv
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Hauptverfasser: Yuan, Chen, Lu, Yizhou, Chen, Zu-Cheng, Liu, Lang
Format: Preprint
Veröffentlicht: 2025
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author Yuan, Chen
Lu, Yizhou
Chen, Zu-Cheng
Liu, Lang
author_facet Yuan, Chen
Lu, Yizhou
Chen, Zu-Cheng
Liu, Lang
contents Second-order tensor perturbations induced by primordial fluctuations play a crucial role in probing small-scale physics, but gauge dependence of their energy density has remained a fundamental challenge in cosmological perturbation theory. We address this issue by introducing a boundary condition-based filtering method that extracts physical radiation through the Sommerfeld criterion. We demonstrate that after filtering non-physical modes, the energy density of secondary gravitational waves becomes gauge-invariant and exhibits physically consistent behavior in the sub-horizon limit. This approach provides a unified framework for both adiabatic and isocurvature perturbations, enhancing theoretical predictions and observational signatures of early universe physics.
format Preprint
id arxiv_https___arxiv_org_abs_2501_13691
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Gauge Invariance of Secondary Gravitational Waves
Yuan, Chen
Lu, Yizhou
Chen, Zu-Cheng
Liu, Lang
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Second-order tensor perturbations induced by primordial fluctuations play a crucial role in probing small-scale physics, but gauge dependence of their energy density has remained a fundamental challenge in cosmological perturbation theory. We address this issue by introducing a boundary condition-based filtering method that extracts physical radiation through the Sommerfeld criterion. We demonstrate that after filtering non-physical modes, the energy density of secondary gravitational waves becomes gauge-invariant and exhibits physically consistent behavior in the sub-horizon limit. This approach provides a unified framework for both adiabatic and isocurvature perturbations, enhancing theoretical predictions and observational signatures of early universe physics.
title On the Gauge Invariance of Secondary Gravitational Waves
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2501.13691