Relativistic Shapiro delay measurements of a 2.14-solar-mass millisecond pulsar

Invited

Abstract

Millisecond pulsar (MSP) timing — the process of accounting for every rotation of a rapidly spinning neutron star over long time spans — is a powerful tool for probing realms of physics that are otherwise inaccessible to Earth-based scientists. The neutron star interior equation of state (EoS) is one example of a puzzle in fundamental physics that has been somewhat elucidated by MSP timing. Measuring relativistic Shapiro delay, which is observable in a small subset of MSP binaries, facilitates the unique determination of the masses of both a pulsar and its companion. By combining orbital-phase-specific observations of Shapiro delay using the Green Bank Telescope with data from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 12.5-year data set, we have measured the mass of PSR J0740$+$6620 to be 2.14 ($+$0.10, $-$0.09) solar masses (68\% credibility interval); it is therefore likely to be the most massive neutron star yet observed. Our measurements serve as a strong constraint on the neutron star interior EoS.

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Authors

  • John Yelton

    North Carolina Central University, Louisiana State University, North Carolina State University, Vanderbilt University, University of Virginia, Jefferson Lab, Oak Ridge National Laboratory, Duke University, Georgia Tech Research Institute, General Electric Power, University of the Virgin Islands, University of Florida, University of Alabama, Huntsville, Universities Space Research Association, University of Miami, NC State University, Virginia Polytechnic Institute and State University