Induced gravitational waves in a general cosmological background

Domènech, Guillem

doi:10.1142/s0218271820500285

Cited by 132 publications

(139 citation statements)

References 103 publications

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“…Furthermore the spectrum will be modified for the modes beyond the horizon size at the time of the transition. The typical ∝ f 3 result expected for the spectrum in RD [1025] at these scales is modified as we apply the transfer function upon re-entry of the modes [1026,1027,980,1028] and as an example we find ∝ f for modes re-entering during EMD era. While in principle this modification could allow us to distinguish between RD and modified expansion, the feature in the spectra will only appear at frequencies much below the peak f f peak (β/H) −1 so it could only be visible in exceptionally strong transitions [1028].…”

Section: First Order Phase Transitionsmentioning

confidence: 68%

“…In summary, the GW-induced effects due to an early MD period may strongly depend on how the reheating of the Universe took place. Also, more generally, the thermal history of the early Universe can be probed from the second order induced GW background [979,980,981]. Going back to the case of a stiff epoch preceding the standard RD era, it is worth stressing that Refs.…”

Section: Inflationmentioning

confidence: 99%

“…Going back to the case of a stiff epoch preceding the standard RD era, it is worth stressing that Refs. [980,982] have pointed out that in such a case the amplitude of the second order induced GW spectrum can be greatly enhanced, leading to a potentially observable signals at LISA and other planned observatories.…”

Section: Inflationmentioning

confidence: 99%

See 2 more Smart Citations

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

Allahverdi¹,

Amin²,

Berlin³

et al. 2021

TheOJA

194

140

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It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial black holes, or microhalos during a nonstandard expansion phase have been recently made. In this paper, we review various possible causes and consequences of deviations from radiation domination in the early Universe -taking place either before or after BBN -and the constraints on them, as they have been discussed in the literature during the recent years.

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Section: First Order Phase Transitionsmentioning

confidence: 68%

Section: Inflationmentioning

confidence: 99%

See 1 more Smart Citation

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

Allahverdi¹,

Amin²,

Berlin³

et al. 2021

TheOJA

194

140

View full text Add to dashboard Cite

show abstract

“…In most of the inflationary models, the induced second-order GW is generically negligible compared to the first-order GWs. However, if the power spectrum of scalar perturbations is enhanced at small scales, the second-order GWs can be sizable or even larger than the first-order one [10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Double peaks of gravitational wave spectrum induced from inflection point inflation

Gao

Yang

2021

Eur. Phys. J. C

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We investigate the possibility of inducing the gravitational waves (GWs) with double peak energy spectrum from primordial scalar perturbations in inflationary models with three inflection points. Here the inflection points can be generated from a polynomial potential or generated from a Higgs-like $$\phi ^4$$ ϕ 4 potential with the running of quartic coupling. In such models, the inflection point at large scales predicts the scalar spectral index and tensor-to-scalar ratio to be consistent with current CMB constraints, and the other two inflection points generate two large peaks in the scalar power spectrum at small scales, which can induce GWs with a double peak energy spectrum. We find that for some choices of the parameters the double peak spectrum can be detected by future GW detectors, and one of the peaks around $$f\simeq 10^{-9}{-}10^{-8}$$ f ≃ 10 - 9 - 10 - 8 Hz can also explain the recent NANOGrav signal. Moreover, the peaks of the power spectrum allow for the generation of primordial black holes, which accounts for a significant fraction of dark matter.

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“…The gauge dependence or independence of induced gravitational waves are discussed in these papers [11][12][13][14][15][16]. The induced gravitational waves in different cosmological backgrounds are explored in [17][18][19][20][21][22][23][24][25]. The induced gravitational waves not only probe the primordial density perturbation spectrum on small scales, but also probe the thermal history of the universe [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Measuring the scalar induced gravitational waves from observations

Guo

2021

Eur. Phys. J. C

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We consider the scalar induced gravitational waves from the cosmic microwave background (CMB) observations and the gravitational wave observations. In the $$\Lambda $$ Λ CDM+r model, we constrain the cosmological parameters within the evolution of the scalar induced gravitational waves by the additional scalar power spectrum. The two special cases called narrow power spectrum and wide power spectrum have influence on the cosmological parameters, especially the combinations of Planck18+BAO+BK15+LISA. We also compare these numerical results from four datasets within LIGO, LISA, IPTA and FAST projects, respectively. The constraints from FAST have a significant impact on tensor-to-scalar ratio. Besides, we only consider the relic density of induced gravitational waves with respect to different frequencies from CMB scale to high frequencies including the range of LIGO and LISA.

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Induced gravitational waves in a general cosmological background

Cited by 132 publications

References 103 publications

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

Double peaks of gravitational wave spectrum induced from inflection point inflation

Measuring the scalar induced gravitational waves from observations

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