Séminaire LAM par Alejandra Recio-Blanco

Title: Gaia chemo-kinematical constraints on the nature of Galactic spiral arms

Abstract:
The nature and origin of the spiral arms remain contentious despite nearly six decades of theoretical work. In this talk, I will present the Gaia chemical cartography of the Milky Way disc as a new powerful diagnostic of the spiral arms nature. Using Gaia DR3, we mapped azimuthal variations in the metallicity of both young and old stars and, using young giants (≲150 Myr),  we uncovered local metallicity enhancements at the level of ∼ 0.1 dex, which are statistically correlated with the position of the nearest spiral arms in the Galaxy. They are related to fluctuations in [α/Fe] abundance for young (≲150 Myr) and old (≳2 Gyr) stars, with amplitudes varying according to the studied element. We have then interpret the chemical signatures of the spiral arms using a 2D chemical evolution model, high-resolution Galaxy simulations and zoom-in cosmological simulations. I will present the results of this analysis, providing key insights about the nature of the spiral arms and the crucial gas-stars relationship of Galactic ecology. Finally, future prospects about Gaia DR4 will be discussed.