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Coffee talks

Tuesday 05/12/2023 @ 14:50, Sala riunioni quarto piano e on-line (

Dario Colombo (Argelander-Institut für Astronomie, Universität Bonn, Germany), "Understanding how star formation ends from nearby galaxies to the Milky Way: the molecular gas point-of-view"

Understanding how galaxies cease to form stars represents an outstanding challenge for all galaxy evolution theories. The ``star formation quenching'' can be related to a complex interplay of phenomena such as the AGN activity, the influence of large-scale dynamics, or the environment in which galaxies live. Leveraging kpc-resolved optical data from the CALIFA IFU and molecular gas (CO) observations from APEX, CARMA and ACA telescopes, we have assembled the APEX-EDGE database. This database encompasses integrated information (such as star formation rates, stellar masses, and molecular gas masses) for over 650 objects, enabling a comprehensive study of quenching in nearby galaxies. Our observations using this dataset revealed that the absence of star formation cannot solely be attributed to a scarcity of molecular gas. Instead, decrements in star formation efficiency, which regulates the conversion between molecular gas and stars, play a crucial role in explaining the quenching of galaxies, particularly in their inner regions. In addition, the Milky Way might offer the opportunity to study the development of quenching with the highest resolution possible. Through data from the SEDIGISM and OGHReS surveys, we have analysed molecular gas distribution, together with cloud integrated, star formation, and morphological properties, from spiral arms to inter-arm regions, and from the inner to the outer Galaxy. We have found that the Milky Way possesses a “flocculent” nature of its gaseous disk, typical of the “green valley" galaxies that undergo a gradual reduction of their star formation activity.