The Pandora project – II. How non-thermal physics drives bursty star formation and temperate mass-loaded outflows in dwarf galaxies
Year: 2025
Type: article
Abstract: ABSTRACT Dwarf galaxies provide powerful laboratories for studying galaxy formation physics. Their early assembly, shallow gravitational potentials, and bursty, clustered star formation histories make them especially sensitive to the processes that regulate baryons through multiphase outflows. Using high-resolution, cosmological zoom-in simulations of a dwarf galaxy from the Pandora suite, we explore the impact of stellar radiation, magnetic fields, and cosmic ray feedback on star formation, outflows, and metal retention. We find that our purely hydrodynamical model without non-thermal physics – in which supernova feedback is boosted to reproduce realistic stellar mass assembly – drives violent, overly enriched outflows that suppress the metal content of the host galaxy. Including radiation reduces the clustering of star formation and weakens feedback. However, the additional incorporation of cosmic rays produces fast, mass-loaded, multiphase outflows consisting of both ionized and neutral gas components, in better agreement with observations. These outflows, which entrain a denser, more temperate interstellar medium, exhibit broad metallicity distributions while preserving metals within the galaxy. Furthermore, the star formation history becomes more bursty, in agreement with recent James Webb Space Telescope findings. These results highlight the essential role of non-thermal physics in galaxy evolution and the need to incorporate it in future galaxy formation models.
Institutions: Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, University of Cambridge, European Southern Observatory, SLAC National Accelerator Laboratory, University of Chicago, École Polytechnique Fédérale de Lausanne, University of Oxford, Centre National de la Recherche Scientifique, Institut d'Astrophysique de Paris, Sorbonne Université, Lyon 1 Université, Centre de Recherche Astrophysique de Lyon, University of South Carolina
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: National Science Foundation, National Aeronautics and Space Administration, School Nutrition Foundation, University of Chicago, Dell EMC, Department of Science and Innovation, South Africa, Universities Space Research Association, Durham University, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Universität Stuttgart, Stanford Research Computing Center, Stanford University, Engineering and Physical Sciences Research Council, Science and Technology Facilities Council, H2020 European Research Council
Awards: G1134310069, G1468651527, G1571591014, DiRAC-2.5 - the pathway to DiRAC Phase 3, G1945644245, G2126713887, G2309215924, G2368581224, Peta-5: A National Facility for Petascale Data Intensive Computation and Analytics, G2524606891, G2820069179, G2843074508, G3363198467, Consolidated Grant Astronomy Observation and Theory 2022-2025, G358276009, G3628540479, G414697268, G4251892262, G4498713678, G4720031782, G5274026675, G5385953647, Black holes and their host galaxies: coevolution across cosmic time, From cosmic dawn to high noon: the role of BHs for young galaxies, DiRAC-2.5 DC - Operations 2017-2020, G7386528139, G7633713370, DiRAC: Memory Intensive 2.5y, Connecting galaxy formation and Cosmic Reionization, G825883484, G8322176006, G8914957373, DiRAC: Memory Intensive 2.5x
OpenAlex ID: W4415196378