Closing the Mass Window for Stupendously Large Black Holes

TL;DR

This paper demonstrates that primordial black holes with masses exceeding 10^{11} solar masses cannot constitute a significant dark matter component due to their production of isocurvature perturbations that violate Planck CMB constraints.

Contribution

It provides the first constraints on the existence of stupendously large primordial black holes based on cosmological observations.

Findings

Primordial black holes above 10^{11} solar masses are excluded as dark matter candidates.

Stupendously large black holes generate isocurvature perturbations inconsistent with Planck data.

Abstract

We show that primordial black holes (PBHs) in the $\textit{Stupendously Large Black Hole}$ mass range ($M \gtrsim 10^{11}\,M_\odot$) produce isocurvature perturbations exceeding current $\textit{Planck}$ Cosmic Microwave Background limits, thereby excluding them as a significant dark matter component.