Can “premature collapse” form black holes in the upper and lower mass gaps?

[2509.04574] Can “premature collapse” form black holes in the upper and lower mass gaps?
Authors: Thomas W. Baumgarte , Stuart L. Shapiro View a PDF of the paper titled Can “premature collapse” form black holes in the upper and lower mass gaps?, by Thomas W. Baumgarte and Stuart L. Shapiro View PDF HTML (experimental) Abstract: Observations of gravitational waves from binary black hole mergers, including the recent signals GW231123 and GW230529, have revealed multiple progenitor black holes in the so-called upper and lower mass gaps, respectively.
It is generally assumed that massive stars cannot form black holes in the upper mass gap because pair instabilities in the late stage of stellar evolution disrupt the stars, whereas the lower mass gap refers to the gap between the maximum allowed neutron star mass and the smallest black hole mass expected to form in supernova explosions.
Here we explore a “premature collapse” scenario in which upper mass gap stars collapse and form black holes before they reach the late stage of stellar evolution.
A similar capture scenario can occur to produce black holes in the lower mass gap.