Year: 2026
Type: article
Abstract: Fast analytic and semianalytic studies of neutron stars often require an equation of state (EOS) 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-polytrope relation for the energy density as a function of pressure, ϵ ˆ ( p ˆ ) = a 1 p ˆ Γ 1 + a 2 p ˆ 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 one-term 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 datasets, is then used to choose benchmark EOSs within this region. The selected benchmark EOSs 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. They exhibit superconformal sound-speed peaks with c s 2 / c 2 = 0.59 –0.71 at ϵ ≃ 452–471 MeV fm −3 . This compact analytic family provides reference cases for relativistic stellar-structure tests at current observational scales.
Source: The Astrophysical Journal
Authors: Tian-Shun Chen, Xiao-Ding Zhou, Kilar Zhang
Institutions: Shanghai University, Shanghai Jiao Tong University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7167013940