A Cosmological Framework for Stellar Collisions at High Redshift in Proto-globular Clusters, Nuclear Star Clusters, and Little Red Dots
Abstract Observations and cosmological simulations indicate that the early Universe hosted numerous compact, high-density stellar systems, where close encounters and physical collisions between stars were likely common. We develop a bottom-up framework for stellar dynamics in such environments, spanning systems with and without intermediate-mass and supermassive black holes, and covering regimes where stellar collisions may or may not dominate the evolution. This radially resolved analytic model connects dense star clusters in their cosmological context to observable outcomes mediated by stellar collisions. Initial conditions and environmental properties are drawn from high-resolution cosmological simulations, enabling exploration across a broad region of parameter space. The analytic predictions are validated against Monte Carlo simulations, demonstrating good agreement across key regimes. We find that stellar collisions are ubiquitous in many high-redshift environments, with runaway sequences naturally leading to the formation of very massive stars at early times. Finally, we show that high rates of destructive collisions can rapidly build up extremely dense gaseous environments around massive black holes, potentially providing an analog to the observed population of Little Red Dots.
Authors
- Smadar Naoz (ORCID: https://orcid.org/0000-0002-9802-9279)
- Sanaea C. Rose (ORCID: https://orcid.org/0000-0003-0984-4456)
- Avi Chen (ORCID: https://orcid.org/0000-0002-8859-7790)
- William Lake (ORCID: https://orcid.org/0000-0002-4227-7919)
- Shyam H. Menon (ORCID: https://orcid.org/0000-0001-5944-291X)
- Blakesley Burkhart (ORCID: https://orcid.org/0000-0001-5817-5944)
- Kyle Kremer (ORCID: https://orcid.org/0000-0002-4086-3180)
- Naoki Yoshida (ORCID: https://orcid.org/0000-0001-7925-238X)
- Claire E. Williams (ORCID: https://orcid.org/0000-0003-2369-2911)
- Federico Marinacci
- Mark Vogelsberger
Institutions
- Rutgers, The State University of New Jersey (US)
- Dartmouth College (US)
- Northwestern University (US)
- Philipps University of Marburg (DE)
- University of California, Los Angeles (US)
- University of California System (US)
- Flatiron Institute (US)
- NSF-Simons AI Institute for the Sky (US)
- Massachusetts Institute of Technology (US)
- The University of Tokyo (JP)
- National Institute for Astrophysics (IT)
- University of Bologna (IT)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2026-10-26
- DOI
- https://doi.org/10.3847/1538-4357/aea577
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- Alfred P. Sloan Foundation
- European Commission
- University of California, Los Angeles
- Office of Advanced Research Computing, Rutgers, The State University of New Jersey
- Japan Society for the Promotion of Science