Massive pulsars in compact binaries
|Date||11 September 2019|
The maximum mass of a neutron star constrains the properties of ultradense matter and the possible outcomes of double neutron star mergers. Compact binary millisecond pulsars (with orbital periods shorter than about a day) are a rapidly-growing pulsar population, and provide a good opportunity to search for the most massive neutron stars. In this talk I will present observations and detailed modeling of an extremely irradiated companion to a millisecond pulsar. Applying a new method to measure the velocity of both sides of the companion star, we found that the binary hosts one of the most massive neutron stars known to date, with a mass of 2.27 [+0.17-0.15] Msun. A 2.3 Solar-mass neutron star rules out most currently proposed equations of state, casting doubt on the existence of exotic forms of matter in the core. I will also review the neutron star mass distribution in light of this and more recent discoveries.