An ultraluminous nascent millisecond pulsar

If the ultraluminous source (ULX) M82 X-2 sustains its measured spin-up value of $\dot{\nu }={10}^{-10}{\mathrm{s}}^{-2}$, it will become a millisecond pulsar in less than ${10}^5$ years. The observed (isotropic) luminosity of ${10}^{40}$ erg/s also supports the notion that the neutron star will spin up to a millisecond period upon accreting about $0.1{\mathrm{M}}_{\odot }$—the reported hard X-ray luminosity of this ULX, together with the spin-up value, implies torques consistent with the accretion disk extending down to the vicinity of the stellar surface, as expected for low values of the stellar dipole magnetic field ($B\lesssim {10}^9$G). This suggests a new channel of millisecond pulsar formation—in high-mass X-ray binaries (HMXBs)—and may have implications for studies of gravitational waves, and possibly for the formation of low-mass black holes through accretion-induced collapse.