Scalar Induced Gravitational Waves Review

Domènech, Guillem

doi:10.3390/universe7110398

Cited by 330 publications

(257 citation statements)

References 333 publications

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“…For an interesting historical review of the dark matter candidates, we refer the reader to [2]. Regarding reviews that focus on gravitational waves applied to PBHs and the different constraints to account for dark matter, we have [3,14,15,39,[88][89][90][91]. Another interesting review with potential applications to PBHs is [92], which is focused on scenarios with deviations from radiation domination in the early Universe.…”

Section: Introductionmentioning

confidence: 99%

PBH Formation from Spherically Symmetric Hydrodynamical Perturbations: A Review

Escrivà

2022

Universe

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Primordial black holes, which could have been formed in the very early Universe due to the collapse of large curvature fluctuations, are currently one of the most attractive and fascinating research areas in cosmology for their possible theoretical and observational implications. This review article presents the current results and developments on the conditions for primordial black hole formation from the collapse of curvature fluctuations in spherical symmetry on a Friedman–Lemaître–Robertson–Walker background and its numerical simulation. We review the appropriate formalism for the conditions of primordial black hole formation, and we detail a numerical implementation. We then focus on different results regarding the threshold and the black hole mass using different sets of curvature fluctuations. Finally, we present the current state of analytical estimations for the primordial black hole formation threshold, contrasted with numerical simulations.

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Section: Introductionmentioning

confidence: 99%

PBH Formation from Spherically Symmetric Hydrodynamical Perturbations: A Review

Escrivà

2022

Universe

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“…The value of ω gw lin is related to the frequency ω lin in the scalar power spectrum (2.1) as ω gw lin = c −1 s ω lin , see [13], with c s the propagation speed of density fluctuations, which we take as constant during the production of GWs. 3 Hence, there is a degeneracy between ω lin and c s for a given value of ω gw lin . The amplitude of the oscillations in (1.1) typically cannot be much larger than A lin ∼ O(10%) due to the non-linearities in processing scalar into tensor fluctuations [9].…”

Section: Sharp Feature: Post-inflationary Contributionmentioning

confidence: 99%

“…LISA sensitivity. To get the dependence of the IR tail on the model parameters, we expand the template for small ω lin f , finding at leading order h 2 Ω GW (f ) ∼ h 2 Ω GW (ω lin f ) 3 . Thus the IR slope is controlled by the combination h 2 Ω GW ω 3 lin , which explains the strong anti-correlation between h 2 Ω GW and ω lin in fig.…”

Section: Sharp Feature: Inflation-era Contributionmentioning

confidence: 99%

“…What is interesting for GW observatories is that these departures from single-field slowroll can lead to an enhancement of scalar fluctuations by orders of magnitude compared to their amplitude at CMB scales. As scalar fluctuations couple to tensor modes at second order in perturbations, they induce gravitational waves during inflation and again after inflation as they reenter the horizon (see [3] for a review focusing on the latter case), both of which contribute to the Stochastic GW Background (SGWB). For these scalar-induced GWs the energy density fraction today scales as Ω GW ∼ 10 −5 P 2 ζ , so that an enhancement in P ζ is crucial for detectability.…”

Section: Introductionmentioning

confidence: 99%

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Detecting primordial features with LISA

Fumagalli,

Pieroni,

Renaux-Petel

et al. 2021

Preprint

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Oscillations in the frequency profile of the stochastic gravitational wave background are a characteristic prediction of small-scale features during inflation. In this paper we present a first investigation of the detection prospects of such oscillations with the upcoming space-based gravitational wave observatory LISA. As a proof of principle, we show for a selection of feature signals that the oscillations can be reconstructed with LISA, employing a method based on principal component analysis. We then perform a Fisher forecast for the parameters describing the oscillatory signal. For a sharp feature we distinguish between the contributions to the stochastic gravitational wave background induced during inflation and in the post-inflationary period, which peak at different frequencies. We find that for the latter case the amplitude of the oscillation is expected to be measurable with < 10% accuracy if the corresponding peak satisfies h 2 Ω GW 10 −12 -10 −11 , while for inflationary-era gravitational waves a detection of the oscillations requires a higher peak amplitude of h 2 Ω GW , as the oscillations only appear on the UV tail of the spectrum. For a resonant feature the detection prospects with LISA are maximised if the frequency of the oscillation falls into the range ω log = 4 to 10. Our results confirm that oscillations in the frequency profile of the stochastic gravitational wave background are a worthwhile target for future detection efforts and offer a key for experimentally testing inflation at small scales.

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“…First, the quantum tensor perturbations generated during inflation, called inflationary or primary GWs [76]. Second, the classical GWs generated by density perturbation, called induced or secondary GWs [77,78] and for a recent review see [79]. There are also the Hawking radiated gravitons [8,[80][81][82], as well as other aspects (see, e.g., [83]), whose implications are going to be examined in a separate work.…”

Section: Gravitational Waves and Bbn/cmb Constraintsmentioning

confidence: 99%

Reheating in Runaway Inflation Models via the Evaporation of Mini Primordial Black Holes

Dalianis

Kodaxis

2022

Galaxies

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We investigate the cosmology of mini Primordial Black Holes (PBHs) produced by large density perturbations that collapse during a stiff fluid domination phase. Such a phase can be realized by a runaway-inflaton model that crosses an inflection point or a sharp feature at the last stage of inflation. Mini PBHs evaporate promptly and reheat the early universe. In addition, we examine two notable implications of this scenario: the possible presence of PBH evaporation remnants in galaxies and a non-zero residual potential energy density for the runaway inflaton that might play the role of the dark energy. We specify the parameter space that this scenario can be realized and we find that a transit PBH domination phase is necessary due to gravitational wave (GW) constraints. A distinct prediction of the scenario is a compound GW signal that might be probed by current and future experiments. We also demonstrate our results employing an explicit inflation model.

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Scalar Induced Gravitational Waves Review

Cited by 330 publications

References 333 publications

PBH Formation from Spherically Symmetric Hydrodynamical Perturbations: A Review

PBH Formation from Spherically Symmetric Hydrodynamical Perturbations: A Review

Detecting primordial features with LISA

Reheating in Runaway Inflation Models via the Evaporation of Mini Primordial Black Holes

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