Final Compact Remnants in Core-collapse Supernovae from 20 to 40 M _⊙: The Lower Mass Gap

Abstract A mass paucity of compact objects in the range ∼2–5 M ⊙ has been suggested by X-ray binary observations, namely, “lower gap.” Gravitational wave detections have unlocked another measurement method, and aLIGO/Virgo observed some candidates gap. We revisit numerical simulations on core-collapse supernovae (CCSNe) for ∼20–40 progenitor stars with different initial explosion energies. As a result, lower energy naturally causes more efficient fallback accretion low-metallicity progenitors, then newborn black holes (BHs) center CCSNe can escape from gap, but neutron cannot easily collapse into BHs gap; nevertheless, final remnants solar-metallicity progenitors stick to If we consider that only drastic be those energies are universal, gap reasonably built. The width depth mainly determined typical CCSN metallicity. One expect future multimessenger observations delineate shape which might constrain properties their progenitors.