Numerically modeling stochastic inflation in slow-roll and beyond

De, Aritra; Mahbub, Rafid

doi:10.1103/physrevd.102.123509

Cited by 17 publications

(14 citation statements)

References 55 publications

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“…It is worth noting that, recently the significant effects of quantum diffusion on curvature perturbations produced during USR, and undeniable consequences of that on PBHs formation have been studied in literatures [122][123][124][125][126][127][128][129][130]. In [127,128] applying the stochastic-δN formalism in USR stage, due to the obtained exponential tail for distribution function of curvature perturbations, an increase about several orders of magnitude in the PBHs abundance in comparison with standard results has been computed.…”

Section: Jcap03(2022)033mentioning

confidence: 85%

Primordial black holes ensued from exponential potential and coupling parameter in nonminimal derivative inflation model

Heydari

Karami

2022

J. Cosmol. Astropart. Phys.

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Here, Primordial Black Holes (PBHs) creation from exponential potential has been inquired, through gravitationally raised friction emanated from the nonminimal coupling between gravity and field derivative setup. Setting a two-parted exponential function of inflaton field as coupling parameter, and fine-tuning of four parameter Cases of our model, we could sufficiently slow down the inflaton owing to high friction during an ultra slow-roll phase. This empowers us to achieve enough enhancement in the amplitude of curvature perturbations power spectra, via numerical solving of Mukhanov-Sasaki equation. Thereafter, we illustrate the generation of four PBHs with disparate masses in RD era, corresponding to our four parameter Cases. Two specimens of these PBHs with stellar 𝒪(10)M ⊙ and earth 𝒪(10-6)M ⊙ masses can be appropriate to explicate the LIGO-VIRGO events, and the ultrashort-timescale microlensing events in OGLE data, respectively. Another two Cases of PBHs have asteroid masses around 𝒪(10-13)M ⊙ and 𝒪(10-15)M ⊙ with abundance of 96% and 95% of the Dark Matter (DM) content of the universe. Furthermore, we scrutinize the induced Gravitational Waves (GWs) ensued from PBHs production in our model. Subsequently, we elucidate that their contemporary density parameter spectra (ΩGW0 ) for all predicted Cases have acmes which lie in the sensitivity scopes of the GWs detectors, thereupon the verity of our conclusions can be verified in view of deduced data from these detectors. At length, our numerical outcomes exhibit a power-law behavior for the spectra of ΩGW0 with respect to frequency as ΩGW0 (f) ∼ (f/fc ) n in the proximity of acmes position. As well, in the infrared regime f ≪ fc , the log-reliant form of power index as n = 3 - 2/ln(fc /f) is attained.

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Section: Jcap03(2022)033mentioning

confidence: 85%

Primordial black holes ensued from exponential potential and coupling parameter in nonminimal derivative inflation model

Heydari

Karami

2022

J. Cosmol. Astropart. Phys.

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“…The PBH mass and abundance formulas ( 22), ( 23) are approximations commonly used in the literature. In truth, the masses follow a distribution around (22), and the abundance is better computed from the compaction function [32,[63][64][65][66], a quantity related but not identical to R k . I leave a compaction-function-based treatment for future work.…”

Section: Discussionmentioning

confidence: 99%

“…Various parameters for the three models considered in [23,31], see Table 1 of [31]. Note that the formula [31] uses to relate the black hole mass M to the wavenumber k differs slightly from (22). M ≈ 2.0 × 10 33 g is the solar mass.…”

Section: Appendix B: Most Probable Pathsmentioning

confidence: 99%

A numerical approach to stochastic inflation and primordial black holes

Tomberg

2021

J. Phys.: Conf. Ser.

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Certain models of cosmic inflation produce strong cosmological perturbations at short length scales, which may later collapse into primordial black holes. To find the statistics of these strong perturbations and the ensuing black holes, it is necessary to go beyond linear perturbation theory. Stochastic inflation provides a way to take the leading non-linear effects into account. In this contribution, I discuss recent progress in numerical computations of stochastic inflation. A numerical approach can include more of the non-linearities than an analytical calculation, and can be applied to single-field inflationary models with any potential.

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“…In the stochastic inflation formalism, one way to compute the curvature perturbation is to exploit -25 - the first order variation of the inflaton field with respect to the background, δφ (1) . The angular terms refer to stochastic averages, which are defined as follows [20,40] δφ (1) n = 1 n sim n sim i=1 φ − φ bg n i (6.8) where φ bg refers to the classical background evolution. In principle, if the inflaton-Langevin equations are simulated for large n sim , any number of these stochastic averages can be computed efficiently and no two trajectories will be the same due to the sourcing from the noise term.…”

Section: Numerical Tests With Ornstein-uhlenbeck Noisementioning

confidence: 99%

Smooth coarse-graining and colored noise dynamics in stochastic inflation

Mahbub¹,

De²

2022

Preprint

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We consider stochastic inflation coarse-grained using a general class of exponential filters. Such a coarse-graining prescription gives rise to inflaton-Langevin equations sourced by colored noise that is correlated in e-fold time. The dynamics are studied first in slowroll for simple potentials using first-order perturbative, semi-analytical calculations which are later compared to numerical simulations. Subsequent calculations are performed using an exponentially correlated noise which appears as a leading order correction to the full slow-roll noise correlation functions of the type ξ(N )ξ(N ) (n) ∼ (cosh [n(N − N ) + 1]) −1 . We find that the power spectrum of curvature perturbations P ζ is suppressed at early e-folds, with the suppression controlled by n. Furthermore, we use the leading order, exponentially correlated noise and perform a first passage time analysis to compute the statistics of the stochastic efold distribution N and derive an approximate expression for the mean number of e-folds N . Comparing analytical results with numerical simulations of the inflaton dynamics, we show that the leading order noise correlation function can be used as a very good approximation of the exact noise, the latter being more difficult to simulate.

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Numerically modeling stochastic inflation in slow-roll and beyond

Cited by 17 publications

References 55 publications

Primordial black holes ensued from exponential potential and coupling parameter in nonminimal derivative inflation model

Primordial black holes ensued from exponential potential and coupling parameter in nonminimal derivative inflation model

A numerical approach to stochastic inflation and primordial black holes

Smooth coarse-graining and colored noise dynamics in stochastic inflation

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