Models of pair-instability supernovae ( PISNe ) predict a gap in black hole ( BH ) masses between \sim 45 M _ { \odot } -120 M _ { \odot } , which is referred to as the upper BH mass-gap .
With the advent of gravitational-wave astrophysics it has become possible to test this prediction , and there is an important associated effort to understand what theoretical uncertainties modify the boundaries of this gap .
In this work we study the impact of rotation on the hydrodynamics of PISNe , which leave no compact remnant , as well as the evolution of pulsational-PISNe ( PPISNe ) , which undergo thermonuclear eruptions before forming a compact object .
We perform simulations of non-rotating and rapidly-rotating stripped helium stars in a metal poor environment ( Z _ { \odot } / 50 ) in order to resolve the lower edge of the upper mass-gap .
We find that the outcome of our simulations is dependent on the efficiency of angular momentum transport , with models that include efficient coupling through the Spruit-Tayler dynamo shifting the lower edge of the mass-gap upwards by \sim 4 \% , while simulations that do not include this effect shift it upwards by \sim 15 \% .
From this , we expect the lower edge of the upper mass-gap to be dependent on BH spin , which can be tested as the number of observed BH mergers increases .
Moreover , we show that stars undergoing PPISNe have extended envelopes ( R \sim 10 - 1000 ~ { } R _ { \odot } ) at iron-core collapse , making them promising progenitors for ultra-long gamma-ray bursts .