Constraining parity violation in gravity with measurements of neutron-star moments of inertia

Nicolás Yunes, Dimitrios Psaltis, Feryal Özel, Abraham Loeb

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Neutron stars are sensitive laboratories for testing general relativity, especially when considering deviations where velocities are relativistic and gravitational fields are strong. One such deviation is described by dynamical, Chern-Simons modified gravity, where the Einstein-Hilbert action is modified through the addition of the gravitational parity-violating Pontryagin density coupled to a field. This four-dimensional effective theory arises naturally both in perturbative and nonperturbative string theory, loop quantum gravity, and generic effective field theory expansions. We calculate here Chern-Simons modifications to the properties and gravitational fields of slowly spinning neutron stars. We find that the Chern-Simons correction affects only the gravitomagnetic sector of the metric to leading order, thus introducing modifications to the moment-of-inertia but not to the mass-radius relation. We show that an observational determination of the moment-of-inertia to an accuracy of 10%, as is expected from near-future observations of the double pulsar, will place a constraint on the Chern-Simons coupling constant of ξ1/45km, which is at least three-orders of magnitude stronger than the previous strongest bound.

Original languageEnglish (US)
Article number064020
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number6
StatePublished - Mar 15 2010

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


Dive into the research topics of 'Constraining parity violation in gravity with measurements of neutron-star moments of inertia'. Together they form a unique fingerprint.

Cite this