What REgulates the growth of GALaxies? A comprehensive study of the building processes of galaxies over 10 Gyr within the REGAL project

Doctorant : VENTOU Emmy

Directeurs : CONTINI Thierry, EPINAT Benoit

Date début : Octobre 2015

Groupe thématique : GAHEC

The formation and evolution of galaxies inside their dark matter haloes is still poorly understood. We do not know yet why the formation of galaxies is so inefficient, especially in the low and high mass regimes. Two simple processes are put forward: baryons must be ejected from galaxies through outflows (feedback effects coming from active galactic nucleus and/or supernovae- driven galactic winds) or do not cool down to collapse inside galaxy halos. Even if theoretical research in these areas of gas inflows and outflows is a very active field, these physical processes are still poorly constrained from observations. The goal of the REGAL project is to contribute significantly to this quest.

The OCEVU/REGAL project: The role of gas inflows and outflows in galaxy evolution will be followed from the early mass assembly of building blocks, when the universe was typically 1-2 Gyr old, down to the formation of the Hubble sequence of morphological types seen in the local universe. Thanks to existing powerful instruments like SINFONI and X-Shooter, and a new generation of observing facilities like MUSE and KMOS on the ESO/VLT, we will constrain and test scenarios of galaxy formation with unprecedented precision, because of their sensitivity and multiplex power. By putting together unique and large datasets representative of the star-forming galaxy population over 10 Gyr, tailored state-of-the-art numerical simulations and the complementary expertise shared by the two OCEVU teams at IRAP and LAM, the REGAL project will end up with major achievements regarding our understanding of the regulation of star formation and the growth of galaxies over cosmological timescales.

Objective and tasks of the PhD: The thesis will be focused on the analysis of MUSE observations and simulations of intermediate-redshift field star-forming galaxies. The different tasks assigned to this PhD work are the following. T1: an active participation to the MUSE data acquisition chain which includes the preparation (targets/field selection, optimal depth, etc), the observations at Paranal, the data reduction and the quality assessment to produce science- ready datacubes. T2: identification and characterization of detected sources in MUSE fields: catalog production and extraction of sub-datacubes, cross-correlation with ancillary data/catalogs (HST, etc.), characterization of close environment. T3: analysis of galaxy kinematics and metallicity: production of various maps (emission-line position/flux/width) for spatially-resolved intermediate-z galaxies and/or 1D integrated spectra for unresolved sources. Deconvolution processes will be investigated in order to increase the spatial resolution. Modeling of galaxy kinematics. Estimate of metallicity profiles for spatialy-resolved galaxies or integrated metallicity for unresolved sources. Estimate of the minor and major galaxies mergers rate. T4: interpretation of observations in the framework of galaxy formation. Accurate comparison with state-of-the-art numerical simulations in order to connect for example metallicity gradients with gas flows.

Long-term perspectives: The level of expertise and the quality of scientific results that will come out from the REGAL project will prepare the PhD student for the long-term perspective through our participation to major ground-based and space facilities foreseen for ~2025, such as MOSAIC on the ESO/E-ELT and the future ESA X-ray facility ATHENA.

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