Updated universal relations for tidal deformabilities of neutron stars from phenomenological equations of state
Abstract
Equation of state (EOS) insensitive relations, socalled universal relations, between the neutron star (NS) compactness, its multipolar tidal deformability coefficients, and between the tidal parameters for binary systems are essential to break degeneracies in gravitational wave data analysis. Here, we validate and recalibrate these universal relations using a large set of almost 2 million phenomenological EOSs that are consistent with current observations. In doing so, we extend universal relations to a larger region of the EOS parameter space, most notably to softer EOSs and larger compactnesses. We show that waveform models that neglect higherthanleadingorder tidal deformations of the NSs accumulate as much as 3.5 radians of dephasing from 20 Hz to merger. We also perform a full Bayesian parameter estimation of the GW170817 data, and we compare the NS radius constraints produced using universal relations from the literature and the updated fits we propose here. We find that the new fits yield a NS radius that is smaller by about 500 meters. This difference is less than the statistical uncertainty on the radius at the signaltonoise ratio of GW170817, but it is significantly larger than the precision anticipated for nextgeneration detectors.
 Publication:

Physical Review D
 Pub Date:
 March 2021
 DOI:
 10.1103/PhysRevD.103.063036
 arXiv:
 arXiv:2012.12151
 Bibcode:
 2021PhRvD.103f3036G
 Keywords:

 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 11 pages, 18 figures