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Primordial Black Holes Arise When The Inflaton Falls

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arxiv 2104.03972 v1 pith:3ZNJ7TTM submitted 2021-04-08 astro-ph.CO gr-qchep-phhep-th

classification astro-ph.COgr-qchep-phhep-th
keywords blackholespbhsstepdarkfluctuationsgravitationalinflaton
verification ladder T0 review T1 audit T2 compute T3 formal

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Primordial Black Holes (PBHs) have entered the forefront of theoretical cosmology, due their potential role in phenomena ranging from gravitational waves, to dark matter, to galaxy formation. While producing PBHs from inflationary fluctuations naively would seem to require a large deceleration of the inflaton from its velocity at the horizon exit of CMB scales, in this work we demonstrate that an acceleration from a relatively small downward step in the potential that is transited in much less than an e-fold amplifies fluctuations as well. Depending on the location of the step, such PBHs could explain dark matter or the black holes detected by the gravitational wave interferometers. The perturbation enhancement has a natural interpretation as particle production due to the non-adiabatic transition associated with the step.

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Cited by 7 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. How deep is the dip and how tall are the wiggles in inflationary power spectra?

    astro-ph.CO 2025-01 conditional novelty 7.0 of 10

    In single-field PBH inflation models, a power-spectrum dip appears precisely when the inflaton velocity does not flip sign, and the peak amplitude scales as the inverse square of the dip amplitude.

  2. Spectator Axions in String Inflation and Primordial Black Holes

    hep-th 2026-07 conditional novelty 6.0 of 10

    In Fibre Inflation, spectator axions with f≲0.1 M_Pl leave the PBH power spectrum unchanged, while for f≳0.1 M_Pl and exponentially small non-perturbative prefactors they can raise P_R from 1.9e-4 to 3.5e-3 and enable...

  3. Light Scalar Fields Foster Production of Primordial Black Holes

    astro-ph.CO 2025-04 conditional novelty 6.0 of 10

    A spectator scalar field with minimal coupling can replace ultra-slow-roll with a turn and tachyonic growth mechanism, producing primordial black holes while reducing fine-tuning.

  4. Reconstructing Primordial Curvature Perturbations via Scalar-Induced Gravitational Waves with LISA

    astro-ph.CO 2025-01 conditional novelty 6.0 of 10

    LISA can reconstruct the primordial curvature power spectrum from scalar-induced gravitational waves, with percent-level precision near the peak and Bayesian tests separating SIGWs from other sources.

  5. Scalar-induced gravitational waves from a box-shaped curvature power spectrum

    gr-qc 2026-07 accept novelty 5.5 of 10

    Analytic SIGW spectra for a log-box curvature power spectrum: narrow-box geometric overlap factor turning IR slope k^{3}ln^{2}k into k^{2}ln^{2}k, plus broad-box product of universal edge functions.

  6. Primordial Black Hole Formation from the Upward Step Model: Avoiding Overproduction

    astro-ph.CO 2024-12 conditional novelty 5.0 of 10

    In upward-step inflation, a non-Gaussian cutoff in curvature perturbations sharply suppresses type-I primordial black hole abundance for h above about 5.9, easing PTA overproduction constraints.

  7. Conservation of superhorizon curvature perturbations at one loop: Backreaction in the in-in formalism and Renormalization

    astro-ph.CO 2025-02 conditional novelty 4.0 of 10

    Superhorizon curvature perturbations remain conserved at one-loop order in single-field inflation with a transient non-slow-roll period when backreaction and renormalization are included.

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