Dissecting the growth of the power spectrum for primordial black holes

Jul 11, 2019
7 pages
Published in:
  • Phys.Rev.D 100 (2019) 10, 103529
  • Published: Nov 27, 2019
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Abstract: (APS)
We consider the steepest rate at which the power spectrum from single field inflation can grow, with the aim of providing a simple explanation for the k4 growth found recently. With this explanation in hand we show that a slightly steeper k5(log k)2 growth is, in fact, possible. Moreover, we argue that the power spectrum after a steep growth cannot immediately decay, but must remain large for the k modes that exit during a ∼2 e-fold period. We also briefly consider how a strong growth can affect the spectral index of longer wavelengths preceding the growth and show that even the conversion of isocurvature modes likely cannot lead to a stronger growth. These results have implications for the formation of primordial black holes and other phenomena that require a large amplitude of power spectrum at short scales.
Note:
  • 7 pages, 3 figures. Typos corrected and references added. Matches version to appear in PRD
  • Cosmology
  • black hole: primordial
  • power spectrum
  • isocurvature: perturbation
  • inflation
  • black hole: formation