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Date: 2014-07-23 - 2014-07-25
Location: Paris, France

The Chalonge School 18th Paris Cosmology Colloquium 2014

The Chalonge School 18th Paris Cosmology Colloquium 2014 “Latest News from the Universe: LambdaWDM, CMB, Warm Dark Matter, Dark Energy, Neutrinos and Sterile Neutrinos”

The new concordance model in agreement with observations: ΛWDM (Lambda-dark energy- Warm Dark Matter). Recently, Warm (keV scale) Dark Matter emerged impressively over CDM (Cold Dark Matter) as the leading Dark Matter candidate. Astronomical evidence that Cold Dark Matter (LambdaCDM) and its proposed tailored baryonic cures do not work at galactic and small scales is staggering. LambdaWDM solves naturally the problems of LambdaCDM and agrees remarkably well with the observations at galactic and small scales as well as large and cosmological scales. In contrast, LambdaCDM simulations only agree with observations at large scales.

In the context of this new Dark Matter situation, which implies novelties in the astrophysical, cosmological, particle and nuclear physics context, the 18th Paris Colloquium 2014 is devoted to the Latest News from the Universe.

2. This Colloquium is within the astrofundamental physics spirit of the Chalonge School, focalised on recent observational and theoretical progress in the CMB, dark matter, dark energy, the new WDM framework to galaxy formation, and the effective theory of the early universe inflation with predictive power in the context of the LambdaWDM Standard Model of the Universe. The Colloquium addresses as well the theory and experimental search for the WDM particle physics candidates (keV sterile neutrinos). Astrophysical constraints including sterile neutrino decays points the sterile neutrino mass m around 2 keV or nearly larger.

In summary, the aim of the meeting is to put together real data : cosmological, astrophysical, particle, nuclear physics data, and hard theory predictive approach connected to them in the framework of the LambdaWDM Standard Model of the Universe.

Two observed quantities crucially constrain the DM nature in an inescapable way independently of the particle physics model: the average DM density rho and the phase space density Q. The observed values of rho and Q in galaxies today robustly point to a keV scale DM particle (WDM) and exclude CDM as well as axion Bose-Einstein condensate DM.

The fermionic quantum pressure of WDM ensures the observed small scale structures as the cores of galaxies and their right sizes (including the dwarf galaxies). N-body simulations in classical (non-quantum) physics do not take into account the fermionic quantum pressure of WDM and produce unreliable results at small scales: That is the reason of the too small core size problem in classical (non quantum) Nbody WDM simulations and its similar dwarf galaxies problem.

Lyman alpha bounds on the WDM particle mass apply only to specific sterile neutrino models and many sterile neutrino models are available today for which the Lyman alpha bounds are unknown. Therefore, WDM cannot be disfavoured in general on the grounds of the Lyman alpha bounds (only valid or specific models), as erroneously stated and propagated in the literature. Astrophysical constraints put the sterile neutrino mass m in the range 1< m <10 keV. Most of the constraints and last results points to m about 2 keV or nearly larger. MARE, KATRIN, ECHO and PTOLEMY experiments could detect such a keV sterile neutrino. It will be a fantastic discovery to detect dark matter in a beta decay or in electron capture. A exciting WDM work to perform is ahead of us.