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The rise of the primordial tensor spectrum from an early scalar-tensor epoch
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Ivonne Zavala Carrasco
Journal of Cosmology and Astroparticle Physics, Volume: 2022, Issue: 08, Start page: 010
Swansea University Authors:
Debika Chowdhury, Gianmassimo Tasinato , Ivonne Zavala Carrasco
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DOI (Published version): 10.1088/1475-7516/2022/08/010
Abstract
Primordial gravitational waves (PGW) produced during inflation span a large range of frequencies, carrying information on the dynamics of the primordial universe. During an early scalar-tensor dominated epoch, the amplitude of the PGW spectrum can be enhanced over a wide range of frequencies. To stu...
| Published in: | Journal of Cosmology and Astroparticle Physics |
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| ISSN: | 1475-7516 |
| Published: |
IOP Publishing
2022
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| Online Access: |
Check full text
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa60779 |
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| Abstract: |
Primordial gravitational waves (PGW) produced during inflation span a large range of frequencies, carrying information on the dynamics of the primordial universe. During an early scalar-tensor dominated epoch, the amplitude of the PGW spectrum can be enhanced over a wide range of frequencies. To study this phenomenon, we focus on a class of scalar-tensor theories, well motivated by high energy theories of dark energy and dark matter, where the scalar is conformally and disformally coupled to matter during the early cosmological evolution. For a conformally dominated epoch, the PGW spectrum has a flat step-like shape. More interestingly, a disformally dominated epoch is characterised by a peaked spectrum with a broken power-law profile, with slopes depending on the scalar-tensor theory considered. We introduce a graphical tool, called broken power-law sensitivity curve, as a convenient visual indicator for understanding whether a given broken power-law profile can be detected by GW experiments. We then analyse the GW spectra for a variety of representative conformal and disformal models, discussing their detectability prospects with the Einstein Telescope (ET), Laser Interferometer Space Antenna (LISA), DECi-hertz Interferometer Gravitational wave Observatory (DECIGO), and Big Bang Observer (BBO). |
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| Keywords: |
Gravitational waves in GR and beyond: theory, physics of the early universe, primordial gravitational waves (theory), gravitational waves / theory |
| College: |
Faculty of Science and Engineering |
| Funders: |
D. C. acknowledges the support of the Supercomputing Wales project, which is part-funded
by the European Regional Development Fund (ERDF) via Welsh Government. D. C. would
also like to thank H. V. Ragavendra for discussions. This work is part-funded by the STFC
grant ST/T000813/1. |
| Issue: |
08 |
| Start Page: |
010 |