This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Cusp–core problem | |
|---|---|
| Name | Cusp–core problem |
| Type | Astrophysical discrepancy |
| Discovered | 1990s |
Cusp–core problem is an astrophysical discrepancy concerning the inner density profiles of dark matter halos inferred from observations of dwarf galaxies, low surface brightness galaxies, and galaxy clusters versus predictions from collisionless cold dark matter simulations. The issue connects to debates involving Vera Rubin, Fritz Zwicky, James Peebles, Simon White, and institutions such as Los Alamos National Laboratory, Institute for Advanced Study, and Max Planck Society where computational cosmology and observational programs developed competing inferences. It influences interpretation of results from surveys and facilities including Hubble Space Telescope, Sloan Digital Sky Survey, Very Large Array, Atacama Large Millimeter Array, and theoretical programs led at Princeton University, Harvard University, and California Institute of Technology.
The origin of the problem lies in comparisons between analytic halo models like the Navarro–Frenk–White profile developed by Julio Navarro, Carlos Frenk, and Simon White and alternative parametrizations used by observers associated with Albert Bosma, Stacy McGaugh, and Marcelo Elizondo. Early simulation work at Los Alamos National Laboratory and Lawrence Berkeley National Laboratory underpinned the universal cusp prediction tied to hierarchical structure formation advocated by George Efstathiou and P. J. E. Peebles. Competing theoretical frameworks include warm dark matter scenarios discussed by teams at CERN, Fermi National Accelerator Laboratory, and California Institute of Technology, and self-interacting dark matter proposed by researchers connected to Columbia University, University of Chicago, and MIT. Seminal conferences at International Astronomical Union meetings and workshops at Kavli Institute for Theoretical Physics brought together proponents from European Southern Observatory, National Aeronautics and Space Administration, and Royal Astronomical Society.
Rotation curve studies by observers such as Vera Rubin's contemporaries and later surveys including Sloan Digital Sky Survey teams, THINGS collaborators, and groups at Australian National University provided inner-density measurements indicating shallower cores in dwarfs studied by John Hibbard, W. J. G. de Blok, and E. L. Schaller. Gravitational lensing analyses by researchers at Space Telescope Science Institute, Max Planck Institute for Astrophysics, and University of Cambridge contrasted cluster-scale profiles measured by Lynds, Ken Freeman, and survey teams from Subaru Telescope. Neutral hydrogen mapping using Very Large Array and Arecibo Observatory data by scientists affiliated with Cornell University, National Radio Astronomy Observatory, and University of Manchester further supported core-like inner slopes in low surface brightness systems studied by Michael Persic and Roberto Giovanelli. Discrepancies in dwarf spheroidal galaxies around the Milky Way were examined by groups at Carnegie Institution for Science, University of Washington, and University of California, Berkeley using stellar kinematics following methods inspired by W. M. Irvine and Oded Regev.
Solutions span astrophysical feedback mechanisms championed by teams at University of Oxford, Yale University, and University of Wisconsin–Madison invoking supernova-driven outflows explored by Avishai Dekel, Romeel Davé, and Andrew Pontzen; baryonic processes modeled by Mark Vogelsberger and Volker Springel; modified dark matter candidates investigated at CERN, Fermi National Accelerator Laboratory, and Brookhaven National Laboratory; and alternative gravity theories discussed by proponents at University of Cambridge and Perimeter Institute for Theoretical Physics. Self-interacting dark matter models receiving attention from Los Alamos National Laboratory and Princeton University researchers aim to produce cores without invoking strong baryonic feedback; warm dark matter proposals advanced at University of California, Santa Cruz and Rutgers University alter small-scale power spectra. Observational campaigns from European Southern Observatory, Keck Observatory, and Gemini Observatory seek signatures discriminating feedback-driven cores by teams including Sandra Faber, Joss Bland-Hawthorn, and Katherine Freese.
High-resolution N-body and hydrodynamical simulations performed by collaborations at Max Planck Institute for Astrophysics, Flatiron Institute, Center for Computational Astrophysics, Harvard-Smithsonian Center for Astrophysics, and Princeton University explored cusp versus core formation under varied baryonic prescriptions by investigators like Volker Springel, Julio Navarro, Mark Vogelsberger, Andrey Kravtsov, and Tom Theuns. Simulation codes developed at Lawrence Livermore National Laboratory, Los Alamos National Laboratory, and NASA Ames Research Center were benchmarked against results from IllustrisTNG, EAGLE, and FIRE projects, with parallel runs at Argonne National Laboratory and Oak Ridge National Laboratory. Methodological advances from John Carlstrom's collaborations and algorithmic contributions from Lars Hernquist and Naoki Yoshida improved modeling of gas cooling, star formation, and feedback processes tested against datasets from Hubble Space Telescope and Chandra X-ray Observatory.
Resolution of the cusp–core discrepancy has consequences for hierarchical assembly paradigms advocated by James Peebles and George Efstathiou, for dark matter particle properties pursued at CERN and Fermi National Accelerator Laboratory, and for small-scale tests of ΛCDM emphasized at Princeton University and Cambridge University. If baryonic feedback resolves cores, programs at Space Telescope Science Institute and European Southern Observatory must revise subgrid prescriptions used by IllustrisTNG and EAGLE teams. If alternative dark matter or modified gravity proposals from Perimeter Institute for Theoretical Physics or Institute for Advanced Study are required, implications extend to experimental searches at Brookhaven National Laboratory and SLAC National Accelerator Laboratory and to interpretations of cosmic microwave background constraints from Planck Collaboration.
Outstanding issues include reconciling high-resolution kinematic data from Gaia and James Webb Space Telescope with predictions from simulations run on supercomputers at Lawrence Berkeley National Laboratory and National Center for Supercomputing Applications by investigators such as Ravan H. M. M. van de Ven and Nitya Kallivayalil. Future wide-area surveys conducted by Vera C. Rubin Observatory, Euclid, and Nancy Grace Roman Space Telescope will refine small-scale structure constraints sought by teams at NASA, ESA, and JAXA. Laboratory searches for dark matter at Gran Sasso National Laboratory, SNOLAB, and Kamioka Observatory and theoretical work at Perimeter Institute for Theoretical Physics and Kavli Institute for Theoretical Physics will further test particle physics resolutions. Continued collaboration among observers at University of California, Santa Cruz, Australian National University, and University of Cambridge and modelers at Max Planck Society and Flatiron Institute remains essential to settle whether cores demand new physics or refined baryonic modeling.