Spectators no more! How even unimportant fields can ruin your Primordial Black Hole model

Understand

In this work we terminate inflation during a phase of Constant Roll by means of a waterfall field coupled to the inflaton and a spectator field.

• The presence of a spectator field means that inflation does not end at a single point, $\phi_e$, but instead has some uncertainty resulting in a stochastic end of inflation.
• We find that even modestly coupled spectator fields can drastically increase the abundance of Primordial Black Holes (PBHs) formed by many orders of magnitude.
• The power spectrum created by the inflaton can be as little as $10^{-4}$ during a phase of Ultra Slow-Roll and still form a cosmologically relevant number of PBHs.