TY - JOUR
T1 - Parametrized equation of state for neutron star matter with continuous sound speed
AU - O'Boyle, Michael F.
AU - Markakis, Charalampos
AU - Stergioulas, Nikolaos
AU - Read, Jocelyn S.
N1 - Funding Information:
We are particularly grateful to John Friedman for helpful discussions and suggestions while performing this work. We also thank Gordon Baym, Charles Gammie, Roland Haas, Vasileios Paschalidis, Cole Miller, J. Ryan Westernacher-Schneider and Leslie Wade for useful suggestions. C. M. was supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 753115 and by COST Action MP1304 NewCompStar. The numerical code for the radial oscillations was derived from a code written by P. Kolitsidou for her B.Sc. thesis at AUTh. N. S. was supported by the ARIS facility of Greek Research and Technology Network (GRNET) in Athens (SIMGRAV, SIMDIFF and BNSMERGE allocations) and the Aristotle Cluster at Aristotle University of Thessaloniki (AUTh) and by COST actions No. CA16214 PHAROS, No. CA16104 GWVerse, No. CA17137 G2Net and No. CA18108 QGMM.
Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/10/26
Y1 - 2020/10/26
N2 - We present a generalized piecewise polytropic parametrization for the neutron-star equation of state using an ansatz that imposes continuity in not only pressure and energy density, but also in the speed of sound. The universe of candidate equations of state is shown to admit preferred dividing densities, determined by minimizing an error norm consisting of integral astrophysical observables. Generalized piecewise polytropes accurately reproduce astrophysical observables, such as mass, radius, tidal deformability and mode frequencies, as well as thermodynamic quantities, such as the adiabatic index. This makes the new equations of state useful for parameter estimation from gravitational waveforms. Since they are differentiable, generalized piecewise polytropes can improve pointwise convergence in numerical relativity simulations of neutron stars. Existing implementations of piecewise polytropes can easily accommodate this generalization with the same number of free parameters. Optionally, generalized piecewise polytropes can also accommodate adjustable jumps in sound speed, which allows them to capture phase transitions in neutron star matter.
AB - We present a generalized piecewise polytropic parametrization for the neutron-star equation of state using an ansatz that imposes continuity in not only pressure and energy density, but also in the speed of sound. The universe of candidate equations of state is shown to admit preferred dividing densities, determined by minimizing an error norm consisting of integral astrophysical observables. Generalized piecewise polytropes accurately reproduce astrophysical observables, such as mass, radius, tidal deformability and mode frequencies, as well as thermodynamic quantities, such as the adiabatic index. This makes the new equations of state useful for parameter estimation from gravitational waveforms. Since they are differentiable, generalized piecewise polytropes can improve pointwise convergence in numerical relativity simulations of neutron stars. Existing implementations of piecewise polytropes can easily accommodate this generalization with the same number of free parameters. Optionally, generalized piecewise polytropes can also accommodate adjustable jumps in sound speed, which allows them to capture phase transitions in neutron star matter.
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U2 - 10.1103/PhysRevD.102.083027
DO - 10.1103/PhysRevD.102.083027
M3 - Article
AN - SCOPUS:85095111523
SN - 2470-0010
VL - 102
JO - Physical Review D
JF - Physical Review D
IS - 8
M1 - 083027
ER -