I-Love-Q Relations in Neutron Stars and their Applications to Astrophysics, Gravitational Waves and Fundamental Physics

By Kent Yagi, N. Yunes. 2013

332 citations recorded by the source corpus.

The exterior gravitational field of a slowly-rotating neutron star can be characterized by its multipole moments, the first few being the neutron star mass, moment of inertia, and quadrupole moment to quadratic order in spin. In principle, all of these quantities depend on the neutron star's internal structure, and thus, on unknown nuclear physics at supra-nuclear energy densities. We here find relations between the moment of inertia, the Love numbers and the quadrupole moment (I-Love-Q relations) that do not depend sensitively on the neutron star's internal structure. Three important consequences derive from these I-Love-Q relations. On an observational astrophysics front, the measurement of a single member of the I-Love-Q trio would automatically provide information about the other two, even when the latter may not be observationally accessible. On a gravitational wave front, the I-Love-Q relations break the degeneracy between the quadrupole moment and the neutron-star spins in binary inspiral waveforms, allowing second-generation ground-based detectors to determine the (dimensionless) averaged spin to $\mathcal{O}(10)%$, given a sufficiently large signal-to-noise ratio detection. On a fundamental physics front, the I-Love-Q relations allow for tests of General Relativity in the neutron-star strong-field that are both theory- and internal structure-independent. As an example, by combining gravitational-wave and electromagnetic observations, one may constrain dynamical Chern-Simons gravity in the future by more than 6 orders of magnitude more stringently than Solar System and table-top constraints.

Subfields: Astronomy and Astrophysics, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/baf097cf90f9e8ca0c95adb2417c1933ad115006

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Citations in the corpus

Maximum mass, moment of inertia and compactness of relativistic stars (2016, methodology): “The second one is the realisation that universal relations exist between I/M3 and λ (Yagi & Yunes 2013b) and between λ and C (Maselli et al. 2013), so that a universal relation should also exist also between I/M3 and C , although not yet discussed in the literature.”
Tidal Deformability from GW170817 as a Direct Probe of the Neutron Star Radius (2018, background): “It has been reported previously that the individual tidal deformabilities of neutron stars obey a universal relationship with stellar compactness (Yagi & Yunes 2013).”
Born–Infeld inspired modifications of gravity (2017, methodology): “The f−mode universality relations and the I-Love-Q relations of [370, 369] have been investigated in the context of Born-Infield gravity in [330].”
From hadrons to quarks in neutron stars: a review (2017, background): “Intriguing `I-Love-Q’ relations between the moment of inertia, I, of a neutron star, its tidal deformability, λ, and the quadrupole moment, Q, induced by rotation, which are relatively insensitive to the detailed internal neutron star structure have been laid out in [174].”
CONSTRAINING THE SYMMETRY PARAMETERS OF THE NUCLEAR INTERACTION (2012, background): “However, Yagi & Yunes (2013) pointed out that nearly equation-of-state (EOS)-independent relations exist among Qrot, I, and λtid which can be used to break these degeneracies.”
Black hole perturbation theory and gravitational self-force (2021, unknown): “15 These calculations represent one of the major applications of the methods of black hole perturbation theory reviewed in the previous section, and they form part of an ongoing endeavour to include tidal effects in gravitational-wave templates and to infer properties of neutron stars from observed ”