An ultraluminous nascent millisecond pulsar.

W. Kluzniak , J. -P. Lasota (1, 2)

1 IAP - Institut d'Astrophysique de Paris
2 UPMC - Université Pierre et Marie Curie - Paris 6

If the ultraluminous source (ULX) M82 X-2 sustains its measured spin-up value of dot{ν }= 10^{-10} s^{-2}, it will become a millisecond pulsar in less than 10⁵ yr. The observed (isotropic) luminosity of 10⁴⁰ erg s^-1 also supports the notion that the neutron star will spin up to a millisecond period upon accreting about 0.1 M_⊙ - the reported hard X-ray luminosity of this ULX, together with the spin-up value, implies torques consistent with the accretion disc extending down to the vicinity of the stellar surface, as expected for low values of the stellar dipole magnetic field (B ≲ 10⁹ G). This suggests a new channel of millisecond pulsar formation - in high-mass X-ray binaries - and may have implications for studies of gravitational waves, and possibly for the formation of low-mass black holes through accretion-induced collapse.

Keywords: accretion: accretion discs; gravitational waves; magnetic fields; stars: black holes; stars: neutron; pulsars: individual: NuSTAR J095551+6940.8; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - High Energy Astrophysical Phenomena

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

W. Kluzniak, J. -P. Lasota. An ultraluminous nascent millisecond pulsar.. Monthly Notices of the Royal Astronomical Society, 2015, 448, pp.L43-L47. ⟨10.1093/mnrasl/slu200⟩. ⟨insu-03645152⟩