### Abstract

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 language | English (US) |
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Article number | 064020 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 81 |

Issue number | 6 |

DOIs | |

State | Published - Mar 15 2010 |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

**Constraining parity violation in gravity with measurements of neutron-star moments of inertia.** / Yunes, Nicolás; Psaltis, Dimitrios; Ozel, Feryal; Loeb, Abraham.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 81, no. 6, 064020. https://doi.org/10.1103/PhysRevD.81.064020

}

TY - JOUR

T1 - Constraining parity violation in gravity with measurements of neutron-star moments of inertia

AU - Yunes, Nicolás

AU - Psaltis, Dimitrios

AU - Ozel, Feryal

AU - Loeb, Abraham

PY - 2010/3/15

Y1 - 2010/3/15

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=77951586471&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77951586471&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.81.064020

DO - 10.1103/PhysRevD.81.064020

M3 - Article

AN - SCOPUS:77951586471

VL - 81

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 0556-2821

IS - 6

M1 - 064020

ER -