Abstract
Current observations of Neutron Stars present a conflict between Gravitational Wave data
(GW170817), which favors a compact “soft” Equation of State (R ≈ 11.5 − 12.0 km), and X-
ray Pulse Profiling (NICER), which reports systematically larger radii (R ≈ 13 km). We pro-
pose that this “Radius Tension” is not a nuclear physics contradiction, but a geometric signature
of the vacuum lattice transitioning from a coordination number of K = 12 (bulk) to K = 13
(surface). Unlike black holes, where the vacuum transition is gravitationally dampened, neu-
tron stars are supported by degeneracy pressure, allowing the full topological expansion ratio
(ξ = 13/12 ≈ 1.0833) to manifest. This zero-parameter model accurately predicts the observed
radius of PSR J0030+0451 (12.0 km × 1.0833 ≈ 13.0 km) and the maximum mass saturation limit
of PSR J0952-0607 (2.17M
⊙
× 1.0833 ≈ 2.35M
⊙
), effectively resolving the tension without invoking
exotic matter.
INTRODUCTION
The study of supranuclear matter is currently deadlocked by two conflicting observational
datasets. On one hand, tidal deformability measurements from gravitational wave events
(e.g., GW170817) favor a “soft” Equation of State (EOS), predicting a standard neutron
star radius of R ≈ 11.5 − 12.0 km [1]. On the other hand, direct X-ray hotspot mapping
by the NICER mission consistently returns larger values, such as 13.02
+1.24
−1.06
km for PSR
J0030+0451 [2].
Concurrently, the discovery of the “Black Widow” pulsar (PSR J0952-0607) with a mass
of 2.35 ± 0.17M
⊙
challenges the standard Tolman-Oppenheimer-Volkoff (TOV) limit of ≈
2.17M
⊙
for soft EOS models [3].
We propose that these are not separate anomalies. They are the structural consequences
of the Selection-Stitch Model (SSM) [4], which posits that the vacuum lattice undergoes a
topological phase transition from a Face-Centered Cubic (K = 12) bulk to a Sintered Mesh
(K = 13) surface under high curvature. This mechanism has previously been identified in
the remnant horizon of GW250114 [5], where it produced a dampened area inflation.
2
THE GEOMETRIC RADIUS BOOST
In the SSM, the bulk of the star is pinned to the K = 12 state by extreme nucleon density.
However, the surface boundary is a topological defect that requires a coordination number
of K = 13 to close the mesh.
Unlike a black hole event horizon, which is a vacuum boundary compressed by infinite
gravity (resulting in a holographic dampening of the inflation [5]), a neutron star has a
material surface supported by quantum degeneracy pressure. This material support allows
the surface lattice to fully realize the topological transition. We therefore apply the uncon-
strained **Lattice Expansion Factor** (ξ = 13/12) directly to the linear dimension of the
star:
R
SSM
= R
EOS
×
13
12
≈ R
EOS
× 1.0833 (1)
Applying this to the baseline prediction of standard soft Equations of State (R
EOS
≈
12.0 km):
R
pred
= 12.0 km × 1.0833 = 13.0 km (2)
This prediction matches the central value of the NICER measurement for PSR J0030+0451
(13.02 km) with high precision [2], effectively bridging the gap between GW (bulk) and
X-ray (surface) data.
THE SATURATION MASS LIMIT
The stability of the star is defined by the maximum load the lattice can support before
strictly enforcing the K = 12 bulk constraint (collapse). The transition to the K = 13
surface state creates a “Geodesic Cage” effect, increasing the effective stability threshold by
the same topological ratio (13/12):
M
SSM
max
≈ M
T OV
max
×
13
12
≈ M
T OV
max
× 1.0833 (3)
For a standard soft EOS limit of 2.17M
⊙
:
M
SSM
max
≈ 2.17M
⊙
× 1.0833 = 2.35M
⊙
(4)
3
This value matches the mass of the heaviest known neutron star, PSR J0952-0607 (2.35M
⊙
)
[3], suggesting that this object represents the “Lattice Saturation” point of the universe.
CONCLUSION
The SSM provides a unified geometric resolution to the Neutron Star Radius Tension
and the Hyper-massive Mass anomaly. The star is a dual-phase object: a K = 12 bulk
wrapped in a K = 13 skin. This “Geodesic Dome” effect explains why neutron stars appear
physically larger and structurally stronger than nuclear physics alone predicts.
∗
raghu@idrive.com
[1] B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), GW170817: Ob-
servation of Gravitational Waves from a Binary Neutron Star Inspiral, Phys. Rev. Lett. 119,
161101 (2017). https://doi.org/10.1103/PhysRevLett.119.161101
[2] M. C. Miller et al., PSR J0030+0451 Mass and Radius from NICER Data and Implications
for the Properties of Neutron Star Matter, Astrophys. J. Lett. 887, L24 (2019). https://doi.
org/10.3847/2041-8213/ab50c5
[3] R. W. Romani et al., PSR J0952-0607: The Fastest and Heaviest Known Galactic Neutron
Star, Astrophys. J. Lett. 934, L18 (2022). https://doi.org/10.3847/2041-8213/ac8007
[4] R. Kulkarni, The Selection-Stitch Model (SSM): Space-Time Emergence via Evolutionary Nu-
cleation, Zenodo (2026). https://doi.org/10.5281/zenodo.18138227
[5] R. Kulkarni, Lattice Sintering Signatures in the Remnant Horizon of GW250114: Evidence for
a 13/12 Coordination Boost, Zenodo (2026). https://doi.org/10.5281/zenodo.18411594
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