Cosmology and General Relativity

Louvain-La-Neuve

Our research interests range from the understanding of the early universe, the place and time at which the candidate unified theories of Nature may have been at work, to late-time cosmology, data analysis and model testing with cosmological observables.
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.

Members

Projects

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).

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.

Recent publications

Showing 15 publications over 114. Show all publications.

2018

Cosmology in the era of Euclid and the Square Kilometre Array
Sprenger, Tim and Archidiacono, Maria and Brinckmann, Thejs and Clesse, Sébastien and Lesgourgues, Julien
[Abstract] [PDF]
Refereed paper. 6th February.
Observational bounds on extended theories of gravity from energy conditions
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]
Refereed paper. 19th January.
Optical Follow-up of Planck Cluster Candidates with Small Instruments
Vincent Boucher, Simon de Visscher and Christophe Ringeval
[Abstract] [PDF] [Journal]
Refereed paper. 15th January.

2017

LIGO Lo(g)Normal MACHO: Primordial Black Holes survive SN lensing constraints
Garcia-Bellido, Juan and Clesse, Sebastien and Fleury, Pierre
[Abstract] [PDF] [Journal]
Refereed paper. 21st December.
Seven Hints for Primordial Black Hole Dark Matter
Clesse, Sebastien and García-Bellido, Juan
[Abstract] [PDF] [Journal]
Refereed paper. 21st December.
Constraints from microlensing experiments on clustered primordial black holes
García-Bellido, Juan and Clesse, Sebastien
[Abstract] [PDF] [Journal]
Refereed paper. 21st December.
Cosmological constant constraints from observation-derived energy condition bounds and their application to bimetric massive gravity
Alves, M. E. S. and Carvalho, F. C. and de Araujo, J. C. N. and Penna-Lima, M. and Vitenti, S. D. P.
[Abstract] [PDF] [Journal]
Refereed paper. 28th November.
CMB constraints on the inflaton couplings and reheating temperature in $alpha$-attractor inflation
Drewes, Marco and Kang, Jin U and Mun, Ui Ri
[Abstract] [PDF] [Journal]
Refereed paper. 22nd November.
ARS Leptogenesis
Drewes, M. and Garbrecht, B. and Hernandez, P. and Kekic, M. and Lopez-Pavon, J. and Racker, J. and Rius, N. and Salvado, J. and Teresi, D.
[Abstract] [PDF] [Journal]
Refereed paper. 20th November.
Multi-Scale Pipeline for the Search of String-Induced CMB Anisotropies
A. Vafaei Sadr, S. Movahed, M. Farhang, C. Ringeval and F. R. Bouchet
[Abstract] [PDF] [Journal]
Refereed paper. 3rd October.
Stochastic gravitational waves from cosmic string loops in scaling
Christophe Ringeval and Teruaki Suyama
[Abstract] [PDF] [Journal]
Refereed paper. 13th September.
CMB anisotropies from patchy reionisation and diffuse Sunyaev-Zel'dovich effects
Christian Fidler and Christophe Ringeval
[Abstract] [PDF] [Journal]
Refereed paper. 6th September.
General relativistic weak-field limit and Newtonian N-body simulations
Fidler, Christian and Tram, Thomas and Rampf, Cornelius and Crittenden, Robert and Koyama, Kazuya and Wands, David
[Abstract] [PDF] [Journal]
Refereed paper. 4th September.
The effect of early radiation in N-body simulations of cosmic structure formation
Adamek, Julian and Brandbyge, Jacob and Fidler, Christian and Hannestad, Steen and Rampf, Cornelius and Tram, Thomas
[Abstract] [PDF] [Journal]
Refereed paper. 4th September.
Relativistic initial conditions for N-body simulations
Fidler, Christian and Tram, Thomas and Rampf, Cornelius and Crittenden, Robert and Koyama, Kazuya and Wands, David
[Abstract] [PDF] [Journal]
Refereed paper. 4th September.