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  • Formation and evolution of Galaxies

    The main target of the MUSE surveys is to find and study the building blocks of the local, normal galaxies such as our Milky Way, at an epoch when the universe was typically 1 Gyr old. The observation of such objects will be of great value to clarify the way galaxies form. In the commonly accepted hierarchical picture, mass assembly is a long-timescale process that starts early and goes on till the present time. Making the census of large and small objects in the early universe, when the cosmic age was 1 Gyr, and studying their properties, will set strong constraints on detailed models of hierarchical galaxy formation. In this prospect, the specific questions which one wants to address by studying this population of objects are the following: how did galaxies like our Milky Way assemble from small fragments? What are the stellar and gaseous masses of these fragments? What are the masses of the dark matter haloes they are hosted in? What are their typical star formation histories?

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    In this simulated MUSE deep field, galaxies are coloured according to their distance (i.e. apparent redshift), the red objects being the most distant galaxies. A period of time spanning 13 Gyr is covered in this exposure. The most distant objects are the precursor of today’s galaxies and are observed when the universe was only 5% of its present age

    Distant galaxies are extremely faint and can only be found by their ionized Hydrogen emission. MUSE will be able detect these in large numbers ( 15,000) through a set of nested surveys of different area and depth. The deepest survey will require very long integrations (80 hrs each field) and will reach a factor 100 better limiting flux than is achieved currently with narrow band imaging. These surveys will simultaneously address the following science goals:

    - Study of intrinsically faint galaxies at high redshift, including determination of their luminosity function and clustering properties
    - Detection of ionized Hydrogen emission out to the epoch of reionization, study of the cosmic web, and determination of the nature of the reionization
    - Study of the physics of Lyman break galaxies, including their winds and feedback to the intergalactic medium
    - Spatially resolved spectroscopy of luminous distant galaxies, including lensed objects
    - Search of late-forming population III objects
    - Study of active nuclei at intermediate and high redshifts
    - Mapping of the growth of dark matter haloes
    - Identification of very faint sources detected in other bands
    - Serendipitous discovery of new classes of objects.

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    An HST image of the lensing cluster Abell 1689, a prime candidate for strong lensing studies with MUSE

    Multi-wavelength coverage of the same fields by MUSE, ALMA, and JWST will provide nearly all the measurements needed to answer the key questions of galaxy formation.

    PDF - 1.9 Mb
    Galaxy Formation and Evolution Science Case
    Complete description of the galaxy formation and evolution science case