Edges of the Pair-Instability Mass Gap from Helium Core Burning
Year: 2026
Type: article
Abstract: Pair production softens the equation of state in very massive helium cores, producing pulsational mass loss and, at higher masses, complete disruption. The result is a predicted gap in black hole masses. This paper restates the gap edges in helium-core and remnant terms and examines how sensitive the lower edge is to the carbon-oxygen reaction rate that controls the explosion outcome. Using the calculation described in the Methods, the headline results are: gap_lower_BH_Msun = 45, gap_upper_BH_Msun = 130, pulsational_range_MHe = [40, 64], full_disruption_range_MHe = [65, 130]. The remnant gap spans roughly forty-five to one hundred and thirty solar masses in the adopted calculations, while the pulsational regime begins at lower helium-core masses because shedding trims the remnant. A black hole observed inside the gap, such as the primary of GW190521, therefore requires either a formation channel beyond isolated stellar collapse or a shift in the nuclear rate, and the paper quantifies how large that shift would need to be. This study is simulated and computed from stated assumptions; it is not a measurement. All headline numbers in this abstract appear in the deposited results file and are reproduced by running the deposited code without modification.
Author: Aldred, William Alexander
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225824816
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