Research Group
"Origin and Evolution of Galaxies"
Institut d'Astrophysique de Paris UPMC homepage CNRS homepage IAP homepage

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Scientific subjects

The scientists in this group are searching for a coherent description of the formation and evolution of galaxies in the Universe, from the Milky Way, which can be studied with great details, up to galaxies observed out to ancient ages in the history of the Universe.

To perform these studies, the group scientists use a large variety of approaches, made of state-of-the-art observations at many different wavelengths, and theoretical modelling which allow one to interpret these data.

On the one hand, the goal is to better understand the different aspects of the physics in galaxies by relating them to stellar formation, and to the relationships between the different components of galaxies:
   - stars and remains of stellar evolution (compact objects, planetary nebulae, supernovae remanents);
   - gas (atomic, molecular and ionised);
   - dust (diffuse and clustered).
The internal movements of these light-emitting components allow one to trace the dark matter detected within all galaxies.

Moreover, understanding the Local Universes is a necessary step towards interpreting the distant Universe observed with large telescopes, and to put constraints on the history of star formation and of mass accumulation in galaxies. These appear to be closely connected to the large diversity of galaxy morphological types observed at all distances in the Universe.

An important issue is to evaluate the relative contribution of bursts of star formation compared to continuous star formation, and the characteristic time scales of these different phenomena. The present and past star formation can be measured using a galaxy spectral energy distribution and other physical parameters such as chemical abundances, metallicity, and extinction.

Given that interactions and mergers of galaxies are known to play an important role in their evolution, galaxies must also be studied in relation with their environment: groups and clusters of galaxies, and the intra-cluster gas.

One can also establish relationships between the evolution of the baryons within galaxies and the evolution of the dark matter halos in which galaxies are trapped by gravity, by comparing observations with the numerical simulations. One can then better outline the formation epoch of the differents galaxy types, and the decisive steps in their evolution, whether they are linked to the gravitational collapse of the large-scale structures on scales of 10 to 100 megaparsecs, or to interactions on the megaparsec scale.

Last modifications 2021/01/30 - Contact V. de Lapparent
Image : D1 Deep Field from the Legacy Survey of the Canada-France-Hawaï Telescope (CFHTLS)
TERAPIX Data Processing Center (CNRS/INSU - IAP - CEA)