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Spiral structures are commonly found in the local Universe, yet their origins and influence on gas and stars remain debated. A powerful approach to probing these mysteries is mapping the interstellar medium and stellar age across spiral arms. During my PhD, I studied spiral galaxies at z~0.3 and z~0 using IFU data from the MAGPI (MUSE) and TYPHOON surveys. I find azimuthal variations in star formation rate and gas-phase metallicity, supporting density wave theory at both redshifts. However, some galaxies also align with dynamic spiral theory, and one nearby spiral exhibits an azimuthal offset opposite to density wave predictions, possibly due to an ongoing merger. This suggests that no single theory explains all spiral structures at low redshifts. Since observations capture only snapshots over cosmic time, I use Auriga simulations to trace the azimuthal distribution of stellar age over 5 Gyr. I find a younger leading edge in most snapshots, consistent with density wave theory, while gas-rich interactions can erase these azimuthal variations, recovering within 600 Myr. Future studies, such as high-redshift observations and higher time-resolution simulations, will better constrain the long-term evolution of spiral galaxies. |
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