PSR J1311-3430: A Heavyweight Neutron Star with a Flyweight Helium Companion. (arXiv:1210.6884v1 [astro-ph.HE])

PSR J1311-3430: A Heavyweight Neutron Star with a Flyweight Helium Companion. (arXiv:1210.6884v1 [astro-ph.HE]):
We have obtained initial spectroscopic observations and additional photometry
of the newly discovered Pb=94min gamma-ray black-widow pulsar PSR J1311-3430.
The Keck spectra show a He-dominated, nearly H-free photosphere and a large
radial-velocity amplitude of 609.5+/-7.5km/s. Simultaneous seven-color GROND
photometry further probes the heating of this companion, and shows the presence
of a flaring infrared excess. We have modeled the quiescent light curve,
constraining the orbital inclination and masses. Simple heated light-curve fits
give M_NS=2.7Msun, but show systematic light-curve differences. Adding extra
components allows a larger mass range to be fit, but all viable solutions have
M_NS>2.1Msun. If confirmed, such a large M_NS substantially constrains the
equation of state of matter at supernuclear densities.