An Analytical Toy Equation of State for Neutron Stars Consistent with Current Observations
Abstract
Fast analytic and semi-analytic studies of neutron stars often require an equation of state that is convenient to evaluate while producing relativistic stellar sequences compatible with current multimessenger constraints. We construct such a benchmark by scanning a smooth double polytropic relation for the energy density as a function of pressure, ε̂(p̂)=a1p̂Γ1+a2p̂Γ2. The parameters are selected with filters based on massive pulsars, tidal deformability from the binary-neutron-star event GW170817, and NICER mass-radius measurements. A single polytropic baseline scan finds no model passing all filters, whereas a double-polytrope scan identifies a viable region. A curve-integral score, evaluated against public NICER and GW170817 posterior data sets, is then used to choose benchmark equations of state within this region. The selected representatives support Mmax=2.44--2.49 M⊙, with R1.4≃ 11.3 km and Λ1.4=485--$512$, and remain causal on the stable branch. This compact analytic family provides reference cases for relativistic stellar-structure tests at current observational scales.
Versions
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BibTeX
@misc{chen2026analytical,
title = {{An Analytical Toy Equation of State for Neutron Stars Consistent with Current Observations}},
author = {Tian-Shun Chen and Xiao-Ding Zhou and Kilar Zhang},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.00070},
eprint = {2607.00070},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.00070},
}
RIS
TY - UNPB
TI - An Analytical Toy Equation of State for Neutron Stars Consistent with Current Observations
AU - Tian-Shun Chen
AU - Xiao-Ding Zhou
AU - Kilar Zhang
PY - 2026
DA - 2026/07/01
PB - arXiv
DO - 10.48550/arxiv.2607.00070
UR - https://arxiv.org/abs/2607.00070
AB - Fast analytic and semi-analytic studies of neutron stars often require an equation of state that is convenient to evaluate while producing relativistic stellar sequences compatible with current multimessenger constraints. We construct such a benchmark by scanning a smooth double polytropic relation for the energy density as a function of pressure, ε̂(p̂)=a_1p̂^Γ_1+a_2p̂^Γ_2. The parameters are selected with filters based on massive pulsars, tidal deformability from the binary-neutron-star event GW170817, and NICER mass-radius measurements. A single polytropic baseline scan finds no model passing all filters, whereas a double-polytrope scan identifies a viable region. A curve-integral score, evaluated against public NICER and GW170817 posterior data sets, is then used to choose benchmark equations of state within this region. The selected representatives support M_max=2.44--2.49 M_⊙, with R_1.4≃ 11.3 km and Λ_1.4=485--$512$, and remain causal on the stable branch. This compact analytic family provides reference cases for relativistic stellar-structure tests at current observational scales.
ER -