Induced gravitational wave interpretation of PTA data

a complete study for general equation of state

verfasst von: Guillem Domènech, Shi Pi, Ao Wang, Jianing Wang
Abstract: We thoroughly study the induced gravitational wave interpretation of the possible gravitational wave background reported by PTA collaborations, considering the unknown equation of state w of the early universe. We perform a Bayesian analysis of the NANOGrav data using the publicly available PTArcade code together with SIGWfast for the numerical integration of the induced gravitational wave spectrum. We focus on two cases: a monochromatic and a log-normal primordial spectrum of fluctuations. For the log-normal spectrum, we show that, while the results are not very sensitive to w when the GW peak is close to the PTA window, radiation domination is out of the 2σ contours when only the infra-red power-law tail contributes. For the monochromatic spectrum, the 2σ bounds yield 0.1 ≲ w ≲ 0.9 so that radiation domination is close to the central value. We also investigate the primordial black hole (PBH) abundance for both monochromatic and log-normal power spectrum. We show that, in general terms, a larger width and stiffer equation of state alleviates the overproduction of PBHs. No PBH overproduction requires w ≲ 0.57 up to 2-σ level for the monochromatic spectrum. Furthermore, including bounds from the cosmic microwave background, we find in general that the mass range of the PBH counterpart is bounded by 10^-5 M _⊙ ≲ M _PBH ≲ 10^-1 M _⊙. Lastly, we find that the PTA signal can explain the microlensing events reported by OGLE for w ~ 0.7. Our work showcases a complete treatment of induced gravitational waves and primordial black holes for general w for future data analysis.
Organisationseinheit(en): Institut für Theoretische Physik
Externe Organisation(en): Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut)
CAS - Institute of Theoretical Physics
Peking University
University of Tokyo (UTokyo)
Graduate University of Chinese Academy of Sciences
High Energy Accelerator Research Organization (KEK)
Typ: Artikel
Journal: Journal of Cosmology and Astroparticle Physics
Band: 2024
Anzahl der Seiten: 32
ISSN: 1475-7516
Publikationsdatum: 29.08.2024
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Astronomie und Astrophysik
Elektronische Version(en): https://doi.org/10.48550/arXiv.2402.18965 (Zugang: Offen)
https://doi.org/10.1088/1475-7516/2024/08/054 (Zugang: Geschlossen)

BibTeX

@article{a7e95a40191a4713b90c7964d32ffbfb,
title = "Induced gravitational wave interpretation of PTA data: a complete study for general equation of state",
abstract = "We thoroughly study the induced gravitational wave interpretation of the possible gravitational wave background reported by PTA collaborations, considering the unknown equation of state w of the early universe. We perform a Bayesian analysis of the NANOGrav data using the publicly available PTArcade code together with SIGWfast for the numerical integration of the induced gravitational wave spectrum. We focus on two cases: a monochromatic and a log-normal primordial spectrum of fluctuations. For the log-normal spectrum, we show that, while the results are not very sensitive to w when the GW peak is close to the PTA window, radiation domination is out of the 2σ contours when only the infra-red power-law tail contributes. For the monochromatic spectrum, the 2σ bounds yield 0.1 ≲ w ≲ 0.9 so that radiation domination is close to the central value. We also investigate the primordial black hole (PBH) abundance for both monochromatic and log-normal power spectrum. We show that, in general terms, a larger width and stiffer equation of state alleviates the overproduction of PBHs. No PBH overproduction requires w ≲ 0.57 up to 2-σ level for the monochromatic spectrum. Furthermore, including bounds from the cosmic microwave background, we find in general that the mass range of the PBH counterpart is bounded by 10-5 M ⊙ ≲ M PBH ≲ 10-1 M ⊙. Lastly, we find that the PTA signal can explain the microlensing events reported by OGLE for w ~ 0.7. Our work showcases a complete treatment of induced gravitational waves and primordial black holes for general w for future data analysis.",
keywords = "gravitational waves / sources, physics of the early universe, primordial black holes",
author = "Guillem Dom{\`e}nech and Shi Pi and Ao Wang and Jianing Wang",
note = "Publisher Copyright: {\textcopyright} 2024 IOP Publishing Ltd and Sissa Medialab. All rights, including for text and data mining, AI training, and similar technologies, are reserved.",
year = "2024",
month = aug,
day = "29",
doi = "10.48550/arXiv.2402.18965",
language = "English",
volume = "2024",
journal = "Journal of Cosmology and Astroparticle Physics",
issn = "1475-7516",
publisher = "IOP Publishing Ltd.",
number = "8",
}