-- Abstract: Over the last few decades, observations of diffuse gamma-ray emission in the Milky Way– in particular, the excess of GeV gamma-rays detected in the Milky Way’s galactic center, and the massive gamma-ray bubbles (the “Fermi bubbles”) centered about the Milky Way’s disk– have challenged astrophysical models. Nearly all past studies of galactic gamma-ray emission make simplifying assumptions about cosmic ray (CR) propagation that may not be valid (e.g., steady-state equilibrium), but recent numerical breakthroughs have enabled fully time-dependent dynamical evolution of CRs in magnetohydrodynamic (MHD) simulations with resolved, multi-phase small-scale structure in the interstellar medium (ISM), allowing self-consistent comparisons to the Milky Way observations. In this talk, I will present new work in which we model diffuse gamma-ray emission in simulations of Milky Way-mass galaxies with fully-resolved, multi-species CR spectra. We find that the gamma-ray spectrum in the galactic center can fluctuate by up to an order of magnitude on million-year timescales due to highly variable star formation and losses from variable structure in the turbulent ISM. I will also show that Fermi bubble-like features arise from stellar feedback in these simulations. Finally, I will present the first results from a new suite of cosmological simulations in which a dark sector with an ultra-light mediator gives rise to a long-range (kiloparsec-scale) self-interaction. The addition of a long-range dark matter self-interaction has dramatic effects on the formation of galaxies and their host halos, and will be testable by current and upcoming astronomical surveys.

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Mathew Calkins (4:00 PM - 5:30 PM)

Daniel Harlow, Quantum black holes and the emergence of space and time (4:00 PM - 5:30 PM)

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Mathew Calkins (4:00 PM - 5:30 PM)

Marcelo Rozenberg, Simple Memristive Circuits for Brain-Inspired Computing (4:00 PM - 5:30 PM)

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Maria Nocchi, A double-copy picture of strings in AdS (2:00 PM - 3:00 PM)

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Mathew Calkins (4:00 PM - 5:30 PM)

Simon Sponberg, Supra-resonant Dynamics and Self-excited Oscillations in Insect Flight (4:00 PM - 5:30 PM)

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Elizabeth Himwich, w(1+infinity) Symmetry in 4D Gravitational Scattering and Celestial Holography (2:00 PM - 3:15 PM)

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Mathew Calkins (4:00 PM - 5:30 PM)

Priyamvada Natarajan, New Insights Into the Formation of the First Black Holes (4:00 PM)

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Marc Henneaux, The Wheeler-DeWitt equation and the BMS symmetry (2:00 PM - 2:50 PM)

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Neelima Sehgal, Discoveries from CMB-HD (2:00 PM - 3:15 PM)

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Javad Shabani, Chalk Talk: 2025 Nobel Prize Winners Research (3:30 PM - 4:45 PM)

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Mathew Calkins (4:00 PM - 5:30 PM)

Thibault Damour, High-Precision Gravitational Scattering (2:00 PM - 3:00 PM)

Stefano Martiniani, Though This Be Disorder, Yet There Is Order in’t (4:00 PM - 5:30 PM)

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Chrysoula Markou, Building string spectra (12:30 PM - 1:30 PM)

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