What the analysis says
Is cold supranuclear matter stiff (H-1 - Neutron-star matter has a stiff equation of state - no hyperons, bosons, or free quarks near nuclear saturation density) or softened by exotic degrees of freedom (H-44 - The cold supranuclear equation of state is softened by exotic degrees of freedom)? An exhaustive binary, no residual. The prior sat at [0.4, 0.6], favouring softened (pre-2010 hyperon-puzzle consensus). Two two-solar-mass pulsars did all the updating and flipped it to posterior [0.9364, 0.0636]: E-18 - O-1 × HC-12 — Shapiro-delay two-solar-mass measurement anchors the stiff EOS (ratio H-44/H-1 = 0.27) and CG-9 - HC-12 joint over O-18+O-19 (joint ratio ≈ 0.11).
What the model may not capture
The framing over-shoots what the safety leg needs: “stiff, no exotics” is stronger than “central density high enough to stop a micro black hole,” which A-52’s stopping columns actually require — a soft, exotic, ~2 Msun star would still be dense. Two omissions push the same way, both leaving the posterior conservative: no NICER/GW170817 constraints (post-2017, far tighter than these masses), and hybrid EOSs (quark inner core reaching 2 Msun) are filed under H-1 despite containing exotics.
What would help
- Whether NS-survival needs the EOS verdict or only the measured masses — does not exist (the sharper question; masses alone bound central density). 2. NICER/GW170817 constraints — exists, unread. 3. The J0348 white-dwarf cooling systematic, the one link softening must exploit — exists, unread.
Confusions and contradictions
None irreducible. The HC-13 dependence (masses assume GR strong-field dynamics) is real but bounded; A-22’s orbital-decay check largely closes the GR-failure escape.