Tag Archives: dark energy

Probing the dark sector and general relativity at all scales at CERN, Geneve, Switzerland

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The standard cosmological model, based on the theory of general relativity, has been very successful in explaining the observable properties of the cosmos. This success is achieved at the price of assuming that the energy content of the universe is currently dominated by dark contributions; namely, dark matter and dark energy. Only the large-scale gravitational interaction of these components has been detected so far and their properties remain largely unknown, despite great effort, both theoretical and experimental, that has been made to identify any direct interactions between the dark sector and luminous matter. At present we do not even know if the dark components really exist as a new kind of matter or represent a mirage produced by modifications of the laws of gravity.

The rapid improvement in the quality and quantity of observational data requires the development of more precise and detailed descriptions of the predictions of various models for the dark sector. The prediction of each candidate model must be confronted with data on all scales where the model makes calculable predictions that can be tested observationally or experimentally. Progress in this direction requires a strong cooperative effort from experimentalists, observers and theorists.

The purpose of this TH Institute is to bring together experts in theory, experiments and observations interested in dark matter, dark energy and tests of the laws of gravity. It will provide an opportunity to discuss new ideas to probe the dark sector and general relativity at diverse scales. The topics to discuss include the current consistency tests of the standard cosmological model, the identification of new observable signatures of dark matter and dark energy, experimental/observational methods, tests of gravity, and questions such as to what extent it is possible to discriminate among alternative models. The program will include review talks on the state-of-the art in various fields, as well as contributions on more specific topics. A lot of free time will be left for discussions.

Organisers: Diego Blas, Clare Burrage, Justin Khoury, Diana Lopez Nacir, Paolo Pani, Sergey Sibiryakov, Alfredo Urbano

Special Issue “Progress in Cosmology in the Centenary of the 1917 Einstein paper”

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Dear Colleagues,

The first modern cosmological models emerged soon after the discovery of general relativity, putting the study of the Universe as a whole on the firm grounds of an empirically testable, coherent science. In the century since then, cosmology has developed into a precision discipline able to explain the evolution of the Universe in several of its aspects. The goal is under the way, but far than ended. The most stringent open questions remain the nature of dark matter (DM) and of dark energy (DE), and whether General Relativity holds on large cosmological scales.

Of course, many independent observation (anisotropies in CMB, large structure, SNIa data, gravitational lensing, galaxy rotational curves etc.) confirm the necessity of the introduction of these dark components.

However, the existence itself of the most likely DM candidates seem to have been seriously challenged by experiments and or astrophysical observations: e.g. supersymmetric DM and WIMPs by LHC; by LUX, PandaX-II and Xenon100; MACHOs by microlensing. Sterile neutrinos by IceCube and high redshift objects. The properties of the DM in galaxies are presently badly explainable by current theoretical scenarios. At present the nature of DM remains a mystery.

Understanding DE poses an even bigger challenge. Although the cosmological constant may explain the accelerated cosmic expansion, its physical interpretation (as vacuum energy) remains doubtful. Question comes what kind of fields can be responsible for the accelerated cosmic expansion. Several scalar field models of DE induce new type of space-time singularities (e.g. soft singularities). Alternative gravitational theories (e.g. scalar-tensor theories, the emergent gravity model of Verlinde) have been also proposed with the purpose to explain the dark sector.

We invite colleagues to submit papers on the topics:

1: The nature of Dark matter and DE

2: Present/future experiments and observations related to DM, DE and their gravitational effects.

3: Models on DM and DE including the alternative gravitational theories, new fields and their possible interaction with the particles of standard model.

4: Evolution of the Universe, cosmological perturbations, formation of nonlinear structures, first objects.

5: Inflation, initial structure, primordial gravitational waves.

6: Primordial black/white holes, their formation and gravitational waves, their effects on the synthesis of light elements.

7: Anisotropic cosmological models and their perturbations.

8: Exotic singularities, wormholes occurring in cosmological models and in virialized structure.

Dr. Zoltan Keresztes
Prof. Lorenzo Iorio
Prof. Paolo Salucci
Prof. Emmanuel Saridakis
Guest Editors