Laboratoire d’Études du Rayonnement et de la Matière en Astrophysique et Atmosphères

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Lettre du LERMA du 29/10/2020

par Elise blanchard - publié le , mis à jour le

La lettre du LERMA du 29 octobre 2020

Lettre du 29/10/2020

Séminaires à venir

Vendredi 4 décembre 2020, 14h00
via Zoom,
Simulating galaxies at high resolution in their cosmological context with NewHorizon: methods and some key results on galaxy properties and their morphology
Institut d'Astrophysique de Paris
résumé :
Hydrodynamical cosmological simulations are increasing their level of realism by considering more physical processes, having more resolution or larger statistics. However, one usually has to either sacrifice the statistical power of such simulations or the resolution reach within galaxies. I will introduce the NewHorizon project where a zoom-in region of ~(16 Mpc)^3, larger than a standard zoom-in region around a single halo, embedded in a larger box is simulated at high resolution. A resolution of up to 34 pc, typical of individual zoom-in state-of-the-art resimulated halos is reached within galaxies, allowing the simulation to capture the multi-phase nature of the interstellar medium and the clumpy nature of the star formation process in galaxies. I will present and discuss several key fundamental properties of galaxies and of their black holes. Due to its exquisite spatial resolution, NewHorizon captures the inefficient process of star formation in galaxies, which evolve over time from being more turbulent, gas-rich and star-bursting at high redshift. These high redshift galaxies are also more compact, and are more elliptical, disturbed and clumpier until the level of internal gas turbulence decays enough to allow for the formation of stable rotating discs. I will show the origin and persistence of the thin and thick disc components, and explain why the settling of discs ``magically’’ occurs at around a stellar mass of 1e10 Msun.

Vendredi 11 décembre 2020, 14h00
via Zoom,
Investigating the physical processes driving the evolution of baryons in local and high-redshift low-metallicity galaxies
Laboratoire d'Astrophysique de Marseille
résumé :
The chemical enrichment in the interstellar medium of galaxies is regulated by several physical processes: stellar birth and death, dust growth and destruction, galactic inflows and outflows. Understanding the interplay of such processes is essential in order to study galaxy evolution, the chemical enrichment of the Universe through the cosmic epochs and to interpret the available and future observations. Despite the importance of such topics, the contribution of different stellar sources to the chemical enrichment of galaxies, e.g. massive stars exploding as Type II supernovae and low-mass stars, as well as the mechanisms driving the evolution of gas, metal and dust grains, remains controversial. In this seminar, I will revise our current knowledge on these physical processes and the observational challenges. I will then present the results of a recent investigation focused on local low-metallicity galaxies for which the evolution of metals, gas and dust content has been studied. In particular, I will show how the comparison between model predictions and observations can allow us to identify the most relevant physical processes determining the chemical evolution of these systems. I will then discuss how the information derived for local low-metallicity galaxies can be employed to study Lyman-Break Galaxies at the epoch of reionization, which are often considered to be their high-redshift counterparts.

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