Palomar 5 and the Dynamical Inference of Retained Stellar-Mass Black Holes: A TRIDENT Case Analysis

This TRIDENT case analysis evaluates the dynamical inference that the Palomar 5 stellar stream progenitor retained a significant population of stellar-mass black holes prior to tidal dissolution. The analysis separates mechanism from magnitude and distinguishes structural constraints from morphology-dependent inferences. The mechanism under evaluation is conventional gravitational dynamics: stellar-mass black holes formed from massive star evolution may be retained depending on natal kick distributions, undergo mass segregation, dynamically heat the cluster core, and enhance tidal stripping. Gaia astrometry provides the empirical anchor for stream morphology and remnant existence; black holes are not directly detected but inferred through model-dependent dynamical fits. Constraint structure is asymmetric. The upper bound on the retained black hole mass fraction (fBH,0) is structurally constrained by survival-to-now requirements and core velocity dispersion limits on any orbit within the Gaia-constrained posterior. The lower bound is comparatively soft and sensitive to degeneracies in stream morphology, including alternate stripping histories and subhalo encounter models. Primary falsifiers are explicitly defined. If improved core velocity dispersion measurements fall below the minimum dispersion envelope achievable by any retained-black-hole model above a derived threshold f*, the retained-BH explanation is falsified independent of morphology. Survival-to-now provides a complementary hard ceiling on allowed parameter space. The document incorporates explicit retention-hinge uncertainty due to natal kick physics, orbit-posterior coupling, binary contamination control, and degeneracy-aware morphological interpretation. The resulting state vector is: mechanism stable conditional PASS; upper magnitude bound robust; lower magnitude bound soft; headline census unsupported. This case card is produced under USDOP v1.2 and TRIDENT-Z0 discipline, emphasizing falsifiability, parameter-envelope transparency, and separation of signal from inference. KEYWORDS Palomar 5 stellar streams globular cluster evolution stellar-mass black holes black hole retention dynamical heating velocity dispersion natal kicks mass segregation tidal stripping Gaia astrometry orbit posterior subhalo encounters degeneracy analysis parameter envelope TRIDENT framework USDOP falsifiability boundary conditions asymmetric constraints