2025/10/18 by Stuart McAlpine, McAlpine, Stuart · 1 voice
Physics and Astronomy · #Astronomy and Astrophysical Research #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies
paper · doi:10.33232/001c.159142
openalex publication_date 2026/03/17 · openalex created_date 2026/03/18 · openalex updated_date 2026/03/18
We present a publicly available catalogue of massive structures in the nearby Universe, constructed from the Manticore-Local posterior ensemble—a Bayesian field-level reconstruction that infers the underlying dark matter distribution from 2M++ galaxies. We identify massive structures by clustering the central haloes inferred at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> across the 80 posterior realizations, selecting at most one member per realization. These associations serve as probabilistic counterparts to individual massive clusters, each with robust posterior estimates of mass, position, and velocity. The fiducial catalogue contains 401 associations with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo stretchy="false" form="prefix">⟨</mml:mo> <mml:msub> <mml:mi>M</mml:mi> <mml:mn>200</mml:mn> </mml:msub> <mml:mo stretchy="false" form="postfix">⟩</mml:mo> <mml:mo>≥</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>14</mml:mn> </mml:msup> </mml:mrow> </mml:math> ~M, ambiguity rates below 5%, and at least 20 member haloes across the posterior ensemble. We independently validate these systems through stacked Planck thermal Sunyaev–Zel’dovich measurements, which yield significant detections ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>></mml:mo> <mml:mn>3</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> ) showing the expected mass trend, consistent with the established <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Y</mml:mi> </mml:math> – <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>M</mml:mi> </mml:math> scaling relation. Many associations exhibit coherent evolutionary histories, meaning that their progenitor haloes across the posterior ensemble trace consistent merger pathways rather than diverging into unrelated assembly scenarios. Even with only <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> constraints, the inference narrows each system’s possible assembly pathway: progenitor haloes at earlier times occupy Lagrangian volumes 2–5 times smaller than those of mass-matched haloes in unconstrained <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Λ</mml:mi> </mml:math> CDM simulations, reflecting genuine information gain from the observational constraints. Cross-matches with X-ray catalogues reveal systematic mass-scale differences that align with known observational biases: Manticore-Local masses are typically 1.7 times ROSAT-based estimates but agree at unity with weak-lensing-calibrated eROSITA measurements. This illustrates the catalogue’s potential to flag individual systems with significant mass discrepancies for targeted investigation. The resulting catalogue provides an observationally consistent map of massive structures in the local Universe, enabling direct cross-probe comparisons, hybrid analyses combining simulated and observed quantities, and systematic mass-scale studies. All data products are publicly available via cosmictwin.org (https://cosmictwin.org) as a community resource.