Dark Matter Cusps and Cores by Violent Relaxation

Project Information

CuspCore

Grant agreement ID: 101109759

DOI

10.3030/101109759

Project closed

EC signature date 22 March 2023

Start date 1 May 2023

End date 31 May 2025

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 200 538,24

Coordinated by

THE HEBREW UNIVERSITY OF JERUSALEM
Israel

Periodic Reporting for period 1 - CuspCore (Dark Matter Cusps and Cores by Violent Relaxation)

Reporting period: 2023-05-01 to 2025-05-31

Summary of the context and overall objectives of the project

The standard model of cosmology, which describes the universe as being dominated by cold dark matter (DM), has been remarkably successful. However, it faces significant challenges on the scale of individual galaxies. Observations have revealed that some galaxies, from massive ones in the early universe to small dwarf galaxies nearby, appear to contain far less dark matter in their centers than predicted. This discrepancy, known as the "cusp-core problem," questions our understanding of how galaxies form and evolve. Recent discoveries from new observatories like the James Webb Space Telescope have only intensified these questions.

The CuspCore project was launched to address this fundamental problem. Its primary objective was to develop a new, comprehensive theoretical framework to understand the dynamic processes that shape the structure of galaxies and their host DM halos. The project aimed to explain the observed diversity in galaxy structures by modeling key physical mechanisms, such as powerful gas outflows from galactic centers and the gravitational stripping of material from satellite galaxies. By accurately modeling these processes, the project sought to resolve the existing tensions within the standard cosmological model, providing a more complete picture of galaxy formation. The expected impact was a significant advancement in our fundamental knowledge, providing new theoretical tools to the global astrophysics community.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Over the course of the fellowship, the project successfully developed the CuspCore analytical framework. This innovative model is the first to self-consistently describe "violent relaxation," a rapid dynamical process that has been a foundational challenge in astrophysics for over sixty years. The model was used to demonstrate how repeated, powerful outflows of gas driven by supermassive black holes can transform the dense, "cuspy" dark matter centers of massive galaxies into the flat "cores" that are observed.

A major achievement was the development of a new theory for galaxy formation in the early universe, called the "Feedback-Free Starbursts" (FFB) model. This work was motivated by surprising new data from the James Webb Space Telescope and provides a leading explanation for the unexpected abundance of very bright galaxies at cosmic dawn. The project also extended the CuspCore model to describe how satellite galaxies lose mass through tidal forces, explaining the origin of DM-deficient dwarf galaxies. Further work, conducted through the successful mentorship of collaborating students, led to the discovery of new universal scaling relations that describe the internal structure of dark matter halos. Finally, the project also produced emPDF, a novel data-driven method for making high-precision measurements of the Milky Way's mass.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The results of the CuspCore project represent a significant advance beyond the state of the art in theoretical astrophysics. The CuspCore framework provides a powerful and accurate tool that surpasses previous, less consistent models of galaxy structural evolution. It allows for a unified understanding of different dynamical processes that were previously treated in isolation. The FFB model offers a compelling solution to one of the most pressing puzzles to emerge from the James Webb Space Telescope, advancing our understanding of how the very first galaxies formed.

The project's impact is demonstrated by the direct uptake of its results. The emPDF method has been formally adopted by the international Dark Energy Spectroscopic Instrument (DESI) survey, a major observational project, for its analysis of the Milky Way. Furthermore, the theoretical breakthroughs of both the CuspCore and FFB models were central to securing two separate, major international research grants (NSF-BSF), leveraging the MSCA-funded results to attract significant new investment for further research. All key models and codes developed have been made publicly available as open-source software, providing a lasting resource for the scientific community and ensuring the work can be built upon in the future.