Induced gravitational waves as a probe of thermal history of the universe
By Guillem Domènech, Shi Pi, Misao Sasaki. Journal of Cosmology and Astroparticle Physics, 2020
174 citations recorded by the source corpus.
The scalar perturbation induced gravitational waves are a probe of the primordial density perturbation spectrum on small scales. In this paper, we show that they can also probe the thermal history of the universe. We assume the universe underwent a stage with a constant equation of state parameter w, followed by the radiation-dominated stage of the conventional big bang universe. We find that the infrared slope of the power spectrum of the induced stochastic gravitational wave background for decelerating cosmologies is related to the equation of state of the universe. Furthermore, the induced gravitational wave spectrum has in general a broken power-law shape around the scale of reheating. Interestingly, below the threshold 0w= of the equation of state parameter, the broken power-law presents a peak for a Dirac delta peak in the scalar spectrum. For a finite width peak, the threshold changes to w=−1/15 depending on the value of the width. In some cases, such a broken power-law gravitational wave spectrum may degenerate to the spectrum from other sources like phase transitions or global cosmic strings.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/25cc0dd7b99314dce216b6577f324bc060f81404
How researchers see this paper
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In Astronomy and Astrophysics
- Marek Lewicki
- John Ellis
- V. Vaskonen
- Misao Sasaki
- Guillem Domènech
- Chunshan Lin
- B. Carr
- Florian Kuhnel
In Nuclear and High Energy Physics
- Misao Sasaki
- Marek Lewicki
- John Ellis
- Chunshan Lin
- Guillem Domènech
- V. Vaskonen
- B. Carr
- Florian Kuhnel
Citations in the corpus
- Updated predictions for gravitational waves produced in a strongly supercooled phase transition (2020, background): “Beyond the horizon size at the time of production, the spectrum from a short-lasting source, such as a phase transition, is ∝ f3 in standard radiation-dominated expansion [111, 112], but the behaviour changes to ∝ f1 for scales re-entering the horizon during matter domination [113].”
- Gravitational wave constraints on the primordial black hole dominated early universe (2020, background): “Not only they are crucial PBH counterparts [35, 48–50] but constitute powerful probes of the primordial curvature power spectrum on small scales [51, 52] and the thermal history of the universe [37, 38, 53, 54].”