http://arxiv.org/abs/2204.07573
Primordial black holes (PBHs) can be produced by a range of mechanisms in the early universe. A particular formation channel that connects PBHs with inflationary phenomenology invokes enhanced primordial curvature perturbations at small scales. In this paper, we re-examine the impact of the growth of the primordial power spectrum on PBH formation in terms of its implications for the PBH mass function. We show that the mass function is relatively insensitive to the steepness of the growth of the power spectrum and subsequent decay, depending primarily on the peak amplitude and the presence of any plateaus that last more than an e-fold. The shape of the power spectrum can of course be constrained by other tracers, and so understanding the physical limitations on its shape remains a pertinent question. We elaborate on how rapidly the background can transition between different values of the parameters of the Hubble hierarchy, which must ultimately derive from a consistent derivative expansion for the background inflaton field. We discuss artefacts associated with matching calculations, and highlight the robustness of the steepest growth index previously found for single-field inflation with conservatively smoothed transitions and limits on how much the power spectrum can grow.
P. Cole, A. Gow, C. Byrnes, et. al.
Mon, 18 Apr 22
23/34
Comments: 10 pages, 6 figures plus appendices. Comments welcome