A millisecond pulsar in a stellar triple system

TL;DR

This paper reports the discovery and detailed analysis of PSR J0337+1715, a millisecond pulsar in a hierarchical triple system, providing precise measurements of the system's masses and orbital parameters, and offering a new laboratory for testing gravity theories.

Contribution

It presents the first detailed timing and multi-wavelength observations of a pulsar in a triple system with strong gravitational interactions, revealing complex orbital dynamics and evolutionary history.

Findings

Measured pulsar mass as 1.4378(13) solar masses

Determined white dwarf companion masses and orbital inclinations

Identified nearly coplanar and circular orbits indicating complex evolution

Abstract

Gravitationally bound three-body systems have been studied for hundreds of years and are common in our Galaxy. They show complex orbital interactions, which can constrain the compositions, masses, and interior structures of the bodies and test theories of gravity, if sufficiently precise measurements are available. A triple system containing a radio pulsar could provide such measurements, but the only previously known such system, B1620-26 (with a millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of several decades), shows only weak interactions. Here we report precision timing and multi-wavelength observations of PSR J0337+1715, a millisecond pulsar in a hierarchical triple system with two other stars. Strong gravitational interactions are apparent and provide the masses of the pulsar (1.4378(13) Msun, where Msun is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15) Msun and 0.4101(3) Msun), as well as the inclinations of the orbits (both approximately 39.2 degrees). The unexpectedly coplanar and nearly circular orbits indicate a complex and exotic evolutionary past that differs from those of known stellar systems. The gravitational field of the outer white dwarf strongly accelerates the inner binary containing the neutron star, and the system will thus provide an ideal laboratory in which to test the strong equivalence principle of general relativity.