Cosmology and General Relativity
Our data analysis activities have been focused on the Planck satellite measurements and are now turning to the next generation of CMB polarization experiments, such as the CORE satellite. We are also part of the EUCLID and LISA missions, with measurements of the large scale structure of the Universe and gravitational waves, respectively.
Our works on late-time cosmology concern the reionization era and the development of numerical codes to solve for the cosmological perturbations at second order. For this we have developed the SONG code. In particular, our results are used to implement General Relativity effects within the numerical simulations of the formation of the large scale structures.
With respect to early universe cosmology, we explore the observable consequences of Cosmic Inflation and the existence of topological defects, and maintain the public numerical libraries ASPIC and FieldInf allowing to solve any slow-roll and multifield inflationary models.
Another part of our theoretical activities is concerned with modified gravity theories as well as supersymmetric model building for dark matter candidates.
Dark matter and neutrino masses in SUSY models
We study supersymmetric models in which modifications of the neutrino sector, to include a mass term, are connected to the dark matter sector. We analyse if the dark matter particles can be good dark matter candidates by considering cosmological and astrophysical constraints, as well as if the new neutrino sector can accommodate neutrino data.
External collaborators: Suchitat Kulkarni (OAW Wien).
Scalar-tensor theories of gravitation
The strong equivalence principle (SEP) does not hold anymore in various extensions of General Relativity. Its violations can be revealed by the non-universality of free-falling for compact objects and we have developed a generic and effective way to test the SEP in the Cosmic Microwave Background (CMB). A violation of the SEP indeed alters the amplitude of the acoustic oscillations in the primeval plasma. Using the WMAP data, we have contrained a possible SEP violation for the baryons.
Our interests are also focused on the scalar-tensor theories of gravitation and their cosmologies. In a more specific way, we are currently studying a model where the scalar sector is conformally invariant. The effective fluid related to the non-minimally coupled scalar field differs from the other cosmological fluids of radiation by its very particular anisotropic pressure and we are studying its impact on the CMB anisotropies by modifying the CAMB code.
Show past projects.
Sprenger, Tim and Archidiacono, Maria and Brinckmann, Thejs and Clesse, Sébastien and Lesgourgues, Julien
[Abstract] [PDF] 48 pages, 11 figures, 8 tables
Refereed paper. 6th February.
Penna-Lima, M. and Vitenti, S. D. P. and Alves, M. E. S. and de Araujo, J. C. N. and Carvalho, F. C.
[Abstract] [PDF] Submitted to PRD
Refereed paper. 19th January.
Garcia-Bellido, Juan and Clesse, Sebastien and Fleury, Pierre
[Abstract] [PDF] [Journal] 7 pages, 7 figures
Refereed paper. 21st December.