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The missing galaxy question at large scales: challenging the paradigm of galaxy formation


The standard theory of structure formation and evolution via accretion and hierarchical merging of cold dark matter-dominated halos (CDM) is able to explain most of the present observations of the Universe on large scales. However, recent analyses of structure on galactic and subgalactic scales show discrepancies with observations.

Using N-body/SPH cosmological simulations this project will address one of the most severe challenges faced by current models of galaxy formation: the missing satellite question. In particular, numerical simulations of CDM predict over an order of magnitude more subhalos around Milky Way-like galaxies than the number of dwarf galaxies observed around the Milky Way.

This inconsistency persists in overluminous elliptical galaxies (o r fossil groups) that have masses up to 40% of the nearby galaxy cluster Virgo. Fossil groups are missing ~500 satellites with luminosities that occur at the predicted frequency in the Virgo cluster. Moreover, the 'missing galaxies' in fossil groups are as luminous as the Milky Way with a velocity dispersion ~150 km/s.

These mass scales of the missing galaxies are so high that it is much more difficult to invoke gas processes to cause them to disappear. Combining unique data spectroscopy inferred from ESO telescopes for a sample of fossil groups with high-resolution simulations for groups with similar masses will test how pervasive the missing satellite question is on the scale of groups and small clusters.

The research project will address the nature of the transition from objects with a weak substructure function like Milky Way or fossil groups to the abundant substructure of galaxy clusters. It will try to answer to the question whether these systems have properties more similar to galactic systems or to mini-clusters systems. Finally it will assess whether this feature is a result of feedback processes occurred at high redshift.

Call for proposal

See other projects for this call

Funding Scheme

EIF - Marie Curie actions-Intra-European Fellowships


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