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The Rise of Metals and Dust in Galaxies through Cosmic Time

26-30 oct. 2020
 - Marseille (France)

Before the birth of the first generation of stars (population III), the universe contained essentially only hydrogen and helium atoms. But after these first stars ignited, they synthesized in their cores nuclei of atoms heavier and heavier (the rise of metals). Some of these atoms have formed grains of dust, which is now everywhere in the interstellar medium. Dust absorbs and diffuses ultraviolet radiation and optical light, which heats the dust particles that ultimately produce radiation that is re-emitted in the infrared. This process modifies our vision of galaxies and of the universe and has dominated the universe for several billion years (the rise of dust). In addition to the effects of reddening and obscuration, dust grains also play a crucial role in star formation and in the physics and chemistry of the interstellar medium, such as heating and cooling processes, gas dynamics, charge transfer and the formation of H2 molecules. It is therefore important to progress in understanding the history of the formation of heavy elements in the universe as well as the different phases of the duty cycle of dust and the variation of this cycle according to the environment and the cosmic times. Successive generations of IR and sub-mm telescopes (ISO, AKARI, Spitzer, Herschel, ALMA, IRAM) have revolutionized galaxy studies in a wide range of astrophysical environments but can still hardly reach the early universe. Projects in the near future (JWST) and in study (SPICA and Origins Space Telescope) could have performances to reach this ambitious goal and to open the door to the primordial universe. At the same time, many theoretical advances have been made in understanding the composition, physical nature and evolution of the dust cycle and the different processes involved. It is the same for the modeling of the history of the formation of the heavy elements and their ejection in the interstellar, circumgalactic and intergalactic media during the cosmic times in the frame of the formation and the evolution of the galaxies. It is therefore timely to bring together theoretical and observational communities to share what we know about the rise of metals and dust in the universe over a wide range of cosmic times and to discuss effective strategies to best use our powerful current and future facilities.
Discipline scientifique : Planète et Univers - Astrophysique - Cosmologie et astrophysique extra-galactique - Astrophysique galactique - Instrumentation et méthodes pour l'astrophysique

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