ILMATAR: deciphering the cosmic origins of globular clusters and their host galaxies

• Applicant: Natalia Lahén, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558113528

Globular clusters are the densest gravitationally bound conglomerates of stars, ubiquitous in nearly all present-day galaxies. With ages that often exceed 10 billion years, they serve as some of the oldest fossil records of how stars and galaxies formed in the early Universe. Recent James Webb Space Telescope observations have revealed that candidate globular clusters emerged early, only 430 million years after the Big Bang. Furthermore, coeval low-mass galaxies resembling those that host proto-globular clusters seem to exhibit surprisingly strong chemical variations and central black holes with record-breaking masses. These discoveries challenge our current theoretical understanding of the earliest phases of galaxy formation and call for new numerical approaches that explore the origin of globular clusters and black holes in concert with their host galaxies. This Emmy Noether project titled “ILMATAR: deciphering the cosmic origins of globular clusters and their host galaxies” will answer fundamental questions regarding star formation and chemical enrichment in the high-redshift Universe with most advanced numerical simulations. My recent work on low-mass starburst galaxies has shown for the first time how globular clusters form in their galactic environment in idealized settings. The next necessary step is to extend these ultra-high resolution studies to a cosmological context. Leveraging the previous theoretical successes and the extensive astrophysical community at the Zentrum für Astronomie at Heidelberg University, I will lead the international effort to develop the cosmologIcaL enrichMent And clusTering of stARs (ILMATAR) suite of cosmological zoom-in simulations, the first to decipher the origin of globular clusters and their host galaxies in a full cosmological environment. The novel ILMATAR-simulations will make significant progress beyond the state of the art by combining some of the most advanced computational tools optimised to recreate the specific conditions of star formation, stellar evolution, gravitational dynamics and galaxy formation that took place during the first few hundred million years after the Big Bang. Along with my position as the Junior Research Group Leader and the main developer of novel modelling algorithms, I am applying funding for a Postdoctoral researcher to assist in code development, execution and analysis of the simulations, and for two PhD candidates to explore post-processing techniques and synthetic multi-wavelength observations of extreme star-forming environments. The unparalleled fidelity of the ILMATAR-models will predict the chemodynamical structure of proto-globular clusters at sub-parsec resolution, which is crucial to surpass the limiting resolution of state of the art observations of the earliest epochs of star formation. This innovative Emmy Noether project will thus be uniquely suited to take the next steps towards unravelling the mysteries of clustered star formation in the early Universe.

• DFG Programme: Emmy Noether Independent Junior Research Groups