arXiv subjects

Marlon M. S. Mendes

Publications and source records attributed to Marlon M. S. Mendes.

3 recordsLinked to original sources

arXiv2026

Phase-Resolved Ultra-High-Energy Emission Defines an Energetic Boundary for Compact-Object Engines and Dense-Matter Structure

We show that phase-resolved ultra-high-energy emission from LS I $+61^\circ303$ defines a critical energetic boundary linking the compact-object engine, circumstellar interaction depth, and dense-matter structure. Combining the GeV--TeV--UHE spectral transition with an orbital acceleration--transparency sieve and branch-resolved stellar sequences for 116 certified EoS, we find that the measured $25$--$100$ TeV component remains energetically viable for all 116 canonical-mass EoS and therefore does not discriminate among them. EoS discrimination arises only in the deliberately more demanding pure-hadronic $>1$ TeV stress-test construction: at 2.0 kpc and $1.4\,M_\odot$, this boundary gives $I_{45,\rm crit}=1.5504$, with 82 of 116 EoS satisfying the energetic condition at$\dot P_{\rm ref}=3\times10^{-15}\,{\rm s\,s^{-1}}$. A separately applied tidal diagnostic, $Λ_{1.4}\leq580$, is satisfied by 43 EoS, with nine satisfying both conditions. These models span several microscopic classes but occupy a narrow structural region, indicating structural overlap rather than selection of a unique EoS family. A separate GeV power-budget test requires $\dot P_{\rm rot}\gtrsim 5.65\times10^{-14}f_Ω\,{\rm s\,s^{-1}}$ at 2.0 kpc. For $f_Ω\sim1$, the source lies well above the UHE crossing and the EoS discrimination disappears. The UHE observation therefore identifies the engine--environment regime in which differences in neutron-star structure can become observationally discriminating, rather than defining a universal dense-matter selector.

astro-ph.HE↗

arXiv2026

Reconciling GW170817 and GW190814 with a Nonmonotonic Sound-Speed Equation of State

We show that the GW170817-GW190814 tension can be reconciled within General Relativity by a structured causal EoS basin found with a Constrained Evolutionary TOV Discovery pipeline (CETD). The basin contains ~1.4x10^4 unique EoS with M_max = 2.3-2.8 M_sun, R_1.4 = 11.97-12.29 km, Lambda_1.4 <= 580, and double-peaked sound speeds reaching c_s^2/c^2 = 0.86-0.99.

astro-ph.HE↗

arXiv2026

Certified Uncertainty for Surrogate Models of Neutron Star Equations of State via Mondrian Conformal Prediction

We present a multitask surrogate for neutron-star equations of state (EoSs) that delivers \emph{distribution-free}, certified uncertainty via split conformal prediction (CP) and its Mondrian variant. The surrogate ingests a six-parameter piecewise-polytropic representation $(\log_{10}p_1,Γ_1,Γ_2,Γ_3,ρ_1,ρ_2)$ -- with fixed transition densities $ρ_1$ and $ρ_2$ -- and jointly performs (i) validity classification under physical/observational constraints and (ii) regression of $M_{\max}$, $R(M_{\max})$, $R_{1.4}$, and $Λ_{1.4}$. Trained on a balanced set of $40{,}000$ EoSs, the model attains near-perfect discrimination (AUC $\approx 0.997$) and sub-percent relative errors for masses and radii, with few-percent error for tidal deformability. Across $α\in[0.05,0.25]$, empirical coverages closely track $1-α$ for both Standard and Mondrian CP; in conservative regimes, Mondrian yields narrower average physical widths at comparable coverage. To our knowledge, this is the first application of class-conditioned (Mondrian) conformal calibration to neutron-star EoS surrogates, enabling efficient, reproducible, and uncertainty-aware inference; the framework is readily extensible to functional targets (e.g., full $R(M)$ curves).

astro-ph.HE↗