Letters of Intent for 2015

LoI 2015-166
Focus Meeting: The Cosmos as a probe of fundamental physics

Date: 3 August 2015 to 14 August 2015
Location: Honolulu, Hawaii, United States
Contact: Raghunathan Srianand (anand@iucaa.ernet.in)
Coordinating division: Division J Galaxies and Cosmology
Co-Chairs of SOC: Raghunathan Srianand (IUCAA, Post Bag 4, Ganeshkhind, Pune 411007)
Paolo Molaro (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste)
Elisabeth Vangioni (Institut d’Astrophysique de Paris, CNRS, 98 bis Bd Arago, 75014 Paris)
Chair of LOC: ()



a. Cosmology as a probe of fundamental physics
- BBN as a test of fundamental physics
- CMB as a test of fundamental physics
- Large scale structure and the case for dark matter
Future: weak lensing, Euclid

b. Astrophysics as a probe of fundamental physics

- Test of constants with Quasars absorption spectra
- Evolution of the CMB temperature and distance duality tests
- Stellar physics and dark matter
- Stellar physics and constants
Future : GRBs

c. Other experimental constraints from physics

- Implications of the discovery of the Higgs for astrophysics and cosmology
- Status of the dark matter paradigm (accelerator, direct search and astrophysical constraints)
- Local tests of the Equivalence principle (solar system test, Microscope results, test of the constancy of the constants)

d. Gravitation beyond general relativity

- Massive gravity and the landscape of modified gravity
- Gravity waves tests in strong gravitational field as black holes




This workshop addresses hot topics at the boundary between fundamental physics, cosmology and astrophysics. Cosmological and astrophysical observations probe physical regimes of density and temperature that cannot be studied in the laboratory and also give access to the largest scales in space and time. Thus they offer powerful probes to test fundamental physics in unexplored regimes. However, the link between fundamental physics and observations is often difficult to establish since it involves a complex modelling of the systems and a deep understanding of the systematics. This link will be the subject of the workshop.

Scientific Rationale:

The recent observational developments in cosmology and astrophysics have provided our community with high quality large data sets. They have modified the relation between astrophysics and fundamental physics, drawing new questions and offering new probes in physical regimes of density and temperature that cannot be studied in the laboratory as well as giving access to the largest space and time scales. The historical connections between astrophysics and theoretical physics have witnessed tremendous progresses in the past years because of new observations of much higher accuracy. This is in particular the case for primordial nucleosynthesis and indeed the cosmic microwave background, in particular with the results of the Planck satellite. Both allow to set constraints on the deviation from the standard framework (such as the existence of super-symmetric particles, deviations from general relativity). The cosmological model that emerges from these observations and the standard theories of physics requires the introduction of a dark sector containing both dark matter and dark energy. The need for dark matter is today the most compelling argument for the development of physics beyond the standard model of particle physics (e.g. super-symmetry or mirror worlds) and motivates us to test for the validity of general relativity in these regimes. During the past ten years, an active field of research has emerged to test the Einstein equivalence principle that underlies general relativity (in particular through the tests of the constancy of fundamental constants) and to develop theories of gravity beyond general relativity and on their phenomenology. Their signatures are explored which motivates new observations such as the detection of gravity waves or the revival of stellar physics. New experiments, such as Euclid (and also ALMA, SKA, E-ELT/TMT projects), which will provide a wide field observation of weak gravitational lensing, also allow to design new tests. Part of the meeting will thus be dedicated to the prospective concerning what can be learned from these future observations. In principle astrophysics offers powerful probes of new fundamental physics. The link between fundamental physics and observations (physical and astrophysical) is however difficult since it involves a deep understanding of the systematics and thus a careful modelisation of the systems. This workshop addresses hot topics at the boundary between fundamental physics, cosmology and astrophysics, with a prospective view on future developments. We hope to provide to the astrophysical community a place where to discuss some of the recent theoretical developments in order to stimulate new exchanges between the two communities, such as the design of new tests or the use of new astrophysical systems.