Angelis, M.D. orcid.org/0000-0003-3432-8250, Smith, A. orcid.org/0009-0000-2254-1551, Giarè, W. orcid.org/0000-0002-4012-9285 et al. (1 more author) (2024) Gravitational waves in a cyclic Universe: resilience through cycles and vacuum state. Journal of Cosmology and Astroparticle Physics, 2024 (06). ISSN 1475-7516
Abstract
We present a generalised calculation for the spectrum of primordial tensor perturbations in a cyclic Universe, making no assumptions about the vacuum state of the theory and accounting for the contribution of tensor modes produced in the dark energy phase of the previous cycle. We show that these modes have minimal impact on the spectrum observed in the current cycle, except for corrections on scales as large as the comoving Hubble radius today. These corrections are due to sub-horizon modes produced towards the end of the dark energy phase, persisting into the <jats:italic>ekpyrotic</jats:italic> phase of the next cycle as additional quanta. In relation to the vacuum state, we argue that non-Bunch-Davies quanta can easily overwhelm the energy density driving the dark energy phase, potentially compromising the model. Therefore, avoiding backreaction effects sets restrictive constraints on deviations away from the Bunch-Davies vacuum during this phase, limiting the overall freedom to consider alternative vacua in the cyclic Universe.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2024 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 04 Jul 2024 14:26 |
Last Modified: | 04 Jul 2024 14:26 |
Published Version: | http://dx.doi.org/10.1088/1475-7516/2024/06/036 |
Status: | Published |
Publisher: | IOP Publishing |
Refereed: | Yes |
Identification Number: | 10.1088/1475-7516/2024/06/036 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:214226 |
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