2025/12/10 by Aranguren, Eneko, Font, José A., Sanchis-Gual, Nicolas +1
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2512.09554
In relativistic Astrophysics the I-Love-Q relations refer to approximately EoS-independent relations involving the moment of inertia, Love number, and quadrupole moment through some quantities that are normalised by the mass M0 of the background configuration of the perturbative scheme. Since M0 is not an observable quantity, this normalisation hinders the direct applicability of the relations. A common remedy assumes that M0 coincides with the actual mass of the star MS; however, this approximation is only adequate for very slow rotation (when the dimensionless spin parameter is χS<0.1). The more accurate alternative approach, based on the I-Love-Q-δM set of relations, circumvents this limitation by enabling the inference of M0. Here we review both approaches and provide numerical comparisons.