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Programme area: Galaxies and Quasars: Galaxy Formation and Evolution
 

Galaxy Formation and Evolution

Galaxy formation is one of the key problems of modern astronomy. Galaxies in the universe come in a large variety of shapes and sizes, which we refer to as the Hubble sequence. The study of galaxy formation and evolution aims at explaining this variety as well as its statistical properties.

The group focuses on both theoretical and observational problems, with a particular emphasis on the preparation and exploitation of ongoing and future large spectroscopic surveys of the Milky Way. We use the Milky Way, a typical spiral galaxy, as a test case for galaxy formation. Our theoretical expertise includes a wide variety of topics, including high-resolution cosmological simulations of galaxy formation, simulation of gas dynamics in disk galaxies or dynamical modeling of galactic disks.

The observational work of the group is mostly linked to massive stellar spectroscopic surveys. The AIP is the coordinating institute of the RAVE survey, a partner in the SDSS-II collaboration for SEGUE and Supernovae and contributes to the preparation of ESA's next astrometric satellite Gaia.

 


Projects Surveys Codes People Gallery


Current Scientific Projects in the group

As mentioned above, we are interested in many aspects of galaxy formation with theoretical work covering simulations of the hierarchical build-up of galaxies in the ΛCDM cosmology (large scale) to detailed numerical studies of Milky Way-like galaxies ("small" scale). This involves using and developing a variety of numerical codes, to study the physical processes that take place in shaping a galaxy: N-body models, hydrodynamical simulations...

The Milky Way is one of the very few resolved galaxies, and the only one for which we have access to the 6D phase-space. The group puts a particular effort on using simulations to help predict the observable patterns that will help us to solve the puzzle of the Milky Way formation. Combined with large spectroscopic surveys that provides observational constraints, we test different scenarios of galaxy formation.

The group is mainly oriented towards spectroscopic surveys of the Milky Way. The AIP is one of the very few institutes in the world with access to both RAVE data and SDSS/SEGUE data. Our observational projects are focused on using the large amount of data provided by those two surveys to study the details of the formation and of the structure of the Milky Way and its mass distribution.

Some of our current projects are summarized below:
   

Theory and Simulations

  • Galaxy Formation in cosmological simulations

  • Merger events and observable traces

  • Effect of feeback on disk structure

  • Disk formation

  • Gas dynamics in galactic centers
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    Surveys and Observations

  • Structure and dynamics of the Milky Way disk

  • Mass distribution of the Milky Way and Galactic potential

  • Chemical evolution of the disk: chemical patterns and substructures in the abundances plane

  • Star formation history of the Galactic disk and disk heating

  • Origin of the substructures in the solar neighborhood phase-space

  • Surveys

    The group is involved in three major spectroscopic surveys of the Milky Way southern hemisphere. The AIP is the coordinating institute of the RAVE survey, and the group is in charge of the data processing, the validation of the data products and the database and www access for the collaboration. RAVE will result in a catalog of up to 1 million radial velocities and stellar parameters (metallicity, gravity, temperature) for stars in the Milky Way up to an apparent magnitude i=12 (disk dominated).

    The AIP is also a member of the SDSS-II collaboration, with access to the SEGUE and Supernovae data. SEGUE is complementary to the RAVE survey, both in depth and spatial coverage, providing 100,000 spectra for faint stars around the nothern cap of the Milky Way.

    ESA's satellite Hipparcos was the first mission to measure the distance for a vast sample of stars in the solar neighborhood (100,000 stars). Its successor Gaia will be launched in 2011 and will measure the parallax of one billion objects in the Milky Way and Local Group. Its accuracy, combined to the spectroscopic instrument onboard the satellite (the RVS), will provide a direct map of the Milky Way and its phase space. The group is involved in the preparation of the mission and is in charge of various aspects linked to the RVS instrument. Members of the group are developing the external source database (used to validate the radial velocities and stellar parameters), the background subtraction algorithms and part of the first look and validation tools.

    More information for each survey is provided below.

     

    RAVE is an ambitious program to conduct a survey to measure the radial velocities, metallicities and abundance ratios for up to a million stars using the 1.2-m UK Schmidt Telescope of the Anglo-Australian Observatory (AAO), over the period 2003 - 2010. The survey represents a giant leap forward in our understanding of our own Milky Way galaxy, providing a vast stellar kinematic database larger than any other survey proposed for this coming decade. The main data product will be a southern hemisphere survey of about a million stars. This survey would comprise 0.7 million thin disk main sequence stars, 250,000 thick disk stars, 100,000 bulge and halo stars, and a further 50,000 giant stars including some out to 10 kpc from the Sun. RAVE will offer the first truly representative inventory of stellar radial velocities for all major components of the Galaxy. Its completeness and homogeneity will make it an invaluable stand-alone resource, but its full potential will be realised when the radial velocities are combined with proper motions and parallaxes from other sources (USNO, Tycho).
     
    Gaia is an ambitious mission from the European Space Agency, ESA, to chart a three-dimensional map of our Galaxy, the Milky Way, in the process revealing the composition, formation and evolution of the Galaxy. Gaia will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy and throughout the Local Group. This amounts to about 1 per cent of the Galactic stellar population.
    Combined with astrophysical information for each star, provided by on-board multi-colour photometry, these data will have the precision necessary to quantify the early formation, and subsequent dynamical, chemical and star formation evolution of the Milky Way Galaxy.
    Additional scientific products include detection and orbital classification of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our Solar System, through galaxies in the nearby Universe, to some 500 000 distant quasars. It will also provide a number of stringent new tests of general relativity and cosmology.
     
    SEGUE, the Sloan Extension for Galactic Underpinnings and Evolution, and Supernovae are two of the extensions of the Sloan survey (SDSS), for which the AIP is a partner. SEGUE is an imaging and spectroscopic survey of the nothern celestial cap, whose key projects are: (1) the detection of substructures in the Milky Way halo, and (2) defining and refining our knowledge of the Galactic disk. Supernovae, on the other hand, is revisiting at regular intervals one SDSS strip (photomotry alone) to detect extra-galactic supernovae. A by-product of this survey will be variability curves and accurate proper motions for Milky Way stars.
     


    Codes

    The group uses various numerical codes depending on the problem studied. This list presents some public codes used by the group to perform our numerical simulations.


    People

    Current group members are:


    Last change 2007 April 5 by Arnaud Siebert