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Recent observations of AdLIGO and Virgo have shown that the spin measurementsin binary black hole (BH) systems are typically small, which is consistent withthe predictions by the classical isolated binary evolution channel. In thisstandard formation channel, the progenitor of the first-born BH is assumed tohave efficient angular momentum transport. The BH spins in high-mass X-raybinaries (HMXBs), however, have been found consistently to be extremely high.In order to explain the high BH spins, the inefficient angular momentumtransport inside the BH progenitor is required. This requirement, however, isincompatible with the current understanding of conventional efficient angularmomentum transport mechanism. We find that this tension can be highlyalleviated as long as the hypercritical accretion is allowed. We show that, fora case study of Cygnus X-1, the hypercritical accretion cannot only be a goodsolution for the inconsistent assumption upon the angular momentum transportwithin massive stars, but match its other properties reported recently.

Hypercritical Accretion for Black Hole High Spin in Cygnus X-1