The Manticore Project I: a digital twin of our cosmic neighbourhood from Bayesian field-level analysis

McAlpine, Stuart; Jasche, Jens; Ata, Metin; Lavaux, Guilhem; Stiskalek, Richard; Frenk, Carlos S; Jenkins, Adrian

Abstract

We present the first results from the Manticore Project, dubbed Manticore-Local, a suite of Bayesian constrained simulations of the nearby Universe, generated by fitting a physical structure formation model to the 2M++ galaxy catalogue using the borg algorithm. This field-level inference yields physically consistent realizations of cosmic structure, leveraging a non-linear gravitational solver, a refined galaxy bias model, and physics-informed priors. The Manticore-Local posterior realizations evolve within a parent cosmological volume statistically consistent with Lambda-cold dark matter, demonstrated through extensive posterior predictive tests of power spectra, bispectra, initial condition Gaussianity, and the halo mass function. The inferred local supervolume ( Mpc, or ) shows no significant deviation from cosmological expectations; notably, we find no evidence for a large local underdensity, with the mean density suppressed by only per cent relative to the cosmic mean. Our model identifies high-significance counterparts for 14 prominent galaxy clusters – including Virgo, Coma, and Perseus – each within 1 deg of its observed sky position. Across the posterior ensemble, these counterparts are consistently detected with 2σ–4 significance, and their reconstructed masses and redshifts agree closely with observational estimates, confirming the inference’s spatial and dynamical fidelity. The peculiar velocity field recovered by Manticore-Local achieves the highest Bayesian evidence across five independent data sets, surpassing state-of-the-art non-linear models, linear theory, Wiener filtering, and machine learning approaches. Unlike methods yielding only point estimates or using simplified dynamics, Manticore-Local provides a full Bayesian posterior over cosmic structure and evolution, enabling rigorous uncertainty quantification. These results establish Manticore-Local as the most advanced constrained realization suite of the local Universe to date, offering a robust statistical foundation for future studies of galaxy formation, velocity flows, and environmental dependencies in our cosmic neighbourhood.

Citation

McAlpine, S., Jasche, J., Ata, M., Lavaux, G., Stiskalek, R., Frenk, C. S., & Jenkins, A. (2025). The Manticore Project I: a digital twin of our cosmic neighbourhood from Bayesian field-level analysis. Monthly Notices of the Royal Astronomical Society, 540(1), 716-745. https://doi.org/10.1093/mnras/staf767

• Journal Article Type: Article
• Acceptance Date: May 6, 2025
• Online Publication Date: May 9, 2025
• Publication Date: 2025-06
• Deposit Date: Jun 6, 2025
• Publicly Available Date: Jun 6, 2025
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 540
• Issue: 1
• Pages: 716-745
• DOI: https://doi.org/10.1093/mnras/staf767
• Keywords: galaxies: clusters: general, large-scale structure of Universe, galaxies: distances and redshifts
• Public URL: https://durham-repository.worktribe.com/output/3963415