Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries

Understand

Reliable neutron star mass measurements are key to determining the equation-of-state of cold nuclear matter, but these are rare.

• "Black Widows" and "Redbacks" are compact binaries consisting of millisecond pulsars and semi-degenerate companion stars.
• Spectroscopy of the optically bright companions can determine their radial velocities, providing inclination-dependent pulsar mass estimates.
• While inclinations can be inferred from subtle features in optical light curves, such estimates may be systematically biased due to incomplete heating models and poorly-understood variability.