Theoretical Cosmology Research Group

Group Members

Staff:

Thomas Buchert (PR, Head of Group, CRALyon)

- coordination of group activities

Alexandre Arbey (MCF, CRALyon)

- scalar field theories - Dark Energy and Dark Matter

Gérard Massacrier (CR1, CRALyon)

- theories and models

Martin France (Research Technician, CRALyon)

- robust image analysis - Minkowski Functionals

Associates:

Frank Steiner (PR, CRALyon)

- CMB and non-trivial topologies

Sven Lustig (Postdoc, University of Ulm / CRALyon)

- CMB and non-trivial topologies

Nathaniel Obadia (AGPR, ENS-Lyon)

- inhomogeneous inflation and other scalar field models

Students:

Xavier Roy (Ph.D. student, CRALyon)

- scalar field models, backreaction, stability, foliation problem

Alexandre Allès (Ph.D. student, CRALyon)

- relativistic Lagrangian perturbation theory

Fosca Al Roumi (M2 student, CRALyon)

- exact solutions - Dark Matter and Inflation

Associated Students:

Matthias Ostermann (Ph.D. student, Munich, Germany)

- relativistic Lagrangian perturbation theory

Alexander Wiegand (Ph.D. student, University of Bielefeld, Germany)

- multi-scale models and relations to Dark Energy and Dark Matter

Alumni:

Marc Geiller (M1 student, CRALyon)

- stationary effective models

Charly Nayet (M2 student and Ph.D. student, CRALyon)

- exact solutions and generic evolution models

Mickaël Rigault (M2 student, CRALyon)

- statistical measurements of backreaction

Projects

ARTHUS CRAL/IPNL MORPHO CMB

Current Collaborators

Mauro Carfora (University of Pavia, Italy)

- Renormalization of average characteristics, Ricci-Hamilton-Perelman flow

George F.R. Ellis (University of Cape Town, South Africa)

- averaging scales, fundamental issues

Henk van Elst (Merkur Internationale FH Karlsruhe, Germany)

- relations to post-Newtonian theories, averaging problem

Akio Hosoya (Tokyo Institute of Technology, Japan)

- averaging problem, information theory

Masaaki Morita (Okinawa National College of Technology, Japan)

- averaging problem, information theory

Yasushi Suto (University of Tokyo, Japan)

- morphological analyses of fluctuations in the SDSS

Chiaki Hikage (University of Princeton, U.S.A.)

- morphological analyses of fluctuations in the SDSS

Herbert Wagner (University of Munich, Germany)

- morphological analyses, fundamental issues

Martin Kerscher (University of Munich, Germany)

- averaging problem, morphological analyses

Dominik J. Schwarz (University of Bielefeld, Germany)

- perturbation theory, averaging on the lightcone

Aleksandar Rakič (Technical University of Munich, Germany)

- averaging on the lightcone

Nan Li (University of Shenyang, China)

- perturbation theory, information theory

Jean-Michel Alimi (Luth, Observatoire de Paris, France)

- the `morphon' approach, comparison with observations

Julien Larena (University of Cape Town, South Africa)

- averaging on the lightcone, comparison with observations

Pier-Stefano Corasaniti (Luth, Observatoire de Paris, France)

- comparison with observations, CMB, Supernovae

Martin Kunz (University of Genève, Switzerland)

- comparison with observations, CMB, Supernovae

Alberto Carlini (University of Alessandria, Italy)

- variational approach to backreaction, topological issues

Roberto A. Sussman (University of Mexico City, Mexico)

- exact solutions to backreaction

Recent Publications

2008a: 'Dark Energy from structure - a status report'
T. Buchert,
Gen. Rel. Grav. 40, 467-527. (Invited review for special issue on Dark Energy)

2008b: 'Reinterpreting dark energy through backreaction: the minimally coupled morphon field'
J. Larena, T. Buchert and J.-M. Alimi,
in: Proceedings of the 11th Marcel Grossman Meeting, Berlin, Germany ,
H. Kleinert, R.T. Jantzen, R. Ruffini (eds.), World Scientific, 2008, p. 1831.

2008c: 'Ricci flow deformation of cosmological initial data sets'
M. Carfora and T. Buchert,
in: 14th International Conference on Waves and Stability in Continuous Media,
N. Manganaro, R. Monaco, S. Rionero, World Scientific, 2008, 118-127.

2008d: 'On the curvature of the present-day Universe'
T. Buchert and M. Carfora,
Class. Quant. Grav. 25, 195001.

2009a: 'Testing backreaction effects with observations'
J. Larena, J.-M. Alimi, T. Buchert, M. Kunz and P.-S. Corasaniti,
Phys. Rev. D 79, 083011.

2009b: 'Geometrical order-of-magnitude estimates for spatial curvature in realistic models of the Universe'
T. Buchert, G.F.R. Ellis and H. v. Elst,
Gen. Rel. Grav. 41, 2017-2030. (Special Issue in memoriam Jürgen Ehlers)

2009c: 'On the Newtonian limit of the Weyl tensor'
J. Ehlers and T. Buchert,
Gen. Rel. Grav. 41, 2153-2158. (Special Issue in memoriam Jürgen Ehlers)

2009d: 'Proceedings 2nd CRAL-IPNL conference - Dark Energy and Dark Matter: Observations, Experiments and Theories'
Lyon, July 7-11, 2008, France, EAS Publication Series 36, EDP Sciences,
E. Pécontal, T. Buchert, P. Di Stefano, Y. Copin.

2010a: 'Relative information entropy of an inhomogeneous Universe'
M. Morita, T. Buchert, A. Hosoya and N. Li,
`Invisible Universe', Paris 2009. AIP Conference Proceedings: Volume 1241, 1074-1082.

2010b: 'Chaplygin gas and effective description of inhomogeneous universe models in general relativity'
X. Roy and T. Buchert,
Class. Quant. Grav. 27, 175013.

2010c: 'Multiscale cosmology and structure-emerging Dark Energy: a plausibility analysis'
A. Wiegand and T. Buchert,
Phys. Rev. D 82, 023523.

2010d: 'Effective inhomogeneous cosmologies and emerging scalar fields'
T. Buchert, N. Obadia and X. Roy,
New Directions in Modern Cosmology, Leiden 2010.

2010e: 'Multiscale approach to inhomogeneous cosmologies'
A. Wiegand and T. Buchert
New Directions in Modern Cosmology, Leiden 2010.

2010f: 'Towards physical cosmology: geometrical interpretation of Dark Energy, Dark Matter and Inflation without fundamental sources'
T. Buchert,
International Conference on Two Cosmological Models, Mexico City 2010, Universidad Iberoamericana Ciudad de Mexico, in press.

2011a: 'Effective inhomogeneous inflation: curvature inhomogeneities of the Einstein vacuum'
T. Buchert and N. Obadia,
Class. Quant. Grav. F.T.C. 28, 162002.

2011b: 'Global gravitational instability of FLRW backgrounds - interpreting the dark sectors'
X. Roy, T. Buchert, S. Carloni and N. Obadia,
Class. Quant. Grav. 28, 165004.

2011c: 'Toward physical cosmology: focus on inhomogeneous geometry and its non-perturbative effects'
T. Buchert,
Class. Quant. Grav. 28, 164007. (Invited review for focus section on 'inhomogeneous cosmological models and averaging in cosmology')