XIIth School of Cosmology
September 15 - 20, 2014IESC, Cargèse
their impact in the study of galaxies and


The theme of the school is the formation of  large scale structures after the results of the Planck mission. The aim of this school is, after an overview of the standard model containing the inflationary paradigm, to focus on alternatives. The model of inflation, although generally confirmed at phenomenological level with these new data, suffers from conceptual difficulties when we want to use it in the framework of a "realistic" theory ( great unification theory string , for example) . Indeed, as models at large field ( Large Field Inflation) are now virtually eliminated , one has to consider models for which the potential of the inflaton contains a plateau (Small Field Inflation) or several fields (Hybrid Inflation). And in the latter case, one must understand the reason why the non-local gaussianity are so weak . Moreover, the "recent" history of the Universe , since the nucleosynthesis to the formation of structures , requires, so that the observations are consistent with the theory to introduce two ingredients not yet well understood (Dark Matter and Dark Energy).

Context and Scientific Objectives

The standard model of cosmology can be considered as a very effective phenomenological approach to account for observations, but it requires a clarification to the fundamental level. Consider alternatives and their consequences is a way to approach this understanding. This will lead either to reaffirm the current paradigm on more solid theoretical foundations, or to introduce a new one.

In practice, the selected axis is not only to study the different alternatives to very primordial level , but also these alternatives that suggest a different interpretation of the observations . For example, the cosmological constant needed to reproduce the data appears just when large scale structures become nonlinear. Hence, this coincidence might be  due to the presence of inhomogeneities producing a back reaction that we would interpret wrongly as an acceleration of the expansion. Alternatively, one might envisage that the law of gravity dependent on scale or energy in order to interpret these observations.

The topics that are covered in this school are:
  • Standard Model: phenomenological description of the data (e.g., dark matter and dark energy ) , inflation models and slow-roll parameters.
  • Thorough discussion of the currently available data, including the most recent ( those that will be available shortly before school) , including anomalies detected in Planck data, and the forthcoming proposals, such as those based on 21cm or the BAO).
  • Alternatives to inflation models ( Bouncing , String Gas Cosmology, ... ) and their predictions on present and future data.
  • Numerical simulations of the formation of structures with emphasis on the question of how these simulations depend on the standard model and how it would be possible to operate in different contexts.
  • Inhomogeneous models of the universe and spatial averaging methods in Cosmology, or how to account for non-linear effects in general relativity on the mean evolution of the universe.


  • The standard model of cosmology
  • Targeted improvements to the standard model
  • Observations
  • The physics of the early universe: inflation models and gravitation
  • Inhomogeneous Cosmology and the dynamic of the cosmological expansion
  • Formation of cosmological structures

Training goals
The aims of this school is the training of researchers, a reciprocal upgrade of communities involved, and learning new analytical techniques. The residential formula of the school will contribute at this link.

    • The target population consists of a majority of scientists working in the fields of Galaxies and Cosmology, with the aim to favor collaborations.  The researchers that belong to other communities such as theoretical physics, high energy physics, can also be concerned, and especially those associated with data processing/analysis which wish a transfer knowledge, as well as geometers (GR) in view of collaborations.
    • The school is also open to PhD students and postdocs, so they have advanced training, giving them the opportunity to know each other and be appreciated by their elders.
One requires a doctoral level in either Astrophysics or in Theoretical Physics.

Scientific Advisory Committee
François Bouchet, Thomas Buchert, Cédric Deffayet, Mario Novello, Patrick Peter, Christophe Pichon, Joe Silk, Roland Triay

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