Stellar tidal debris structures are excellent probes of galaxy formation and the properties of dark matter on galactic scales. They enable constraints on tidal disruption rates, reveal the hierarchical nature of galaxy formation, and provide precise measurements of the local gravitational potential. However, these studies are complicated by the influence of host galaxy properties on satellite populations, and the limited sample size of observed and simulated galaxies. In this work, we study how the abundance and dynamics of populations of disrupting satellite galaxies change systematically as a function of host galaxy properties. We apply a theoretical model of the phase-mixing process to classify intact satellite galaxies, stellar stream-like and shell-like debris in ~1500 Milky Way-mass systems generated by a semi-analytic galaxy formation code, SatGen. We find that the counts of tidal debris are consistent across all host galaxy models, within a given host mass range, and that all models can have stream-like debris on low-energy orbits, consistent with those observed around the Milky Way. However, we find a preference for stream-like debris on lower-energy orbits in models with a thicker (lower-density) host disk or on higher-energy orbits in models with a more-massive host disk. Importantly, we observe significant halo-to-halo variance across all models. These results highlight the importance of simulating and observing large samples of Milky Way-mass galaxies and accounting for variations in host properties when using disrupting satellites in studies of near-field cosmology and assessing small-scale deviations from ΛCDM. The code designed for this work to produce realistic populations of tidal debris, StreamGen, is publicly available on GitHub.

Given their shallow potential wells, dwarf galaxies are known to undergo significant feedback-driven mass and metal loss from their disk, ejecting material into the circumgalactic medium (CGM) or even beyond the halo entirely. Thus, constraining the mass and metal retention of low-mass halos is a critical component in understanding the baryon cycle of dwarf galaxies and improving modern simulations. In this talk, I present a sample of 64 simulated dwarf galaxies from the Marvel-ous Dwarfs and Marvelous Massive Dwarfs simulations that reproduce observed CGM column densities at z∼0 in various ions. We then characterize the mass and metal retention of these halos and the physical properties of CGM gas to understand how the column densities we measure are tied to the structure and properties of the CGM. We find the majority of baryons within Rvir reside in the CGM and that ∼75% of CGM mass exists at temperatures above T > 10^4.5 K. Although this warmer CGM phase dominates the mass budget, it constitutes a similar fraction of the CGM metal budget as the cool phase. These findings demonstrate the multiphase nature of the CGM, even in the low-mass regime, and emphasizes the importance of a multi-ion approach when studying the CGM of dwarf galaxies.

Understanding the first billion years of galaxy formation requires simulations that capture the complex interplay of star formation, feedback, and dynamical evolution in a rapidly evolving cosmic environment. Current models struggle to reproduce key observations, such as elevated star formation efficiency (SFE) and the early emergence of disk morphology. I will introduce BonFIRE, a new large-volume, high-resolution hydrodynamic simulation designed to bridge the gap between theory and observations from JWST. I will present key results on the stellar mass–halo mass (SMHM) relation, the ultraviolet luminosity function (UVLF) including contributions from Pop III stars, SFE, and the formation and kinematics of early disks. Finally, I will outline future prospects, such as modeling the formation and fate of globular clusters, exploring dark matter–accelerated SFE, and characterizing the environments of proto-Milky Way analogs.

The role of various physical processes in regulating star formation across galaxies and their impact on structural evolution is still not fully understood. Spatially resolved integral field spectroscopy (IFS) has been a key tool in characterization of galaxy properties. Resolved maps of dust attenuation and star formation are an important probe of structural evolution. MSA-3D (JWST NIRSpec/MSA “slit-stepping”) is the first survey to provide high-resolution kpc-scale IFUs across the epoch of thin disk emergence (0.5 < z < 1.5), sampling key rest-optical emission lines in 43 main sequence galaxies. We characterize radial dust attenuation profiles and measure spatially resolved dust attenuation maps for individual galaxies based on the Balmer decrement diagnostic (Hα/Hβ). Based on attenuation and Ha flux maps, we derive attenuation-corrected SFR maps for each galaxy. We find that galaxy-integrated dust attenuation increases with stellar mass -- with more massive galaxies showing higher attenuation. However, we also observe significant diversity in radial dust attenuation profiles, suggesting variations in their individual evolutionary paths. Additionally, dust-corrected SFR maps highlight the importance of accounting for dust effects to accurately measure intrinsic star formation rates.

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