scholarly journals Lagrangian theory of structure formation in relativistic cosmology. VI. Comparison with Szekeres exact solutions

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
Ismael Delgado Gaspar ◽  
Thomas Buchert
Keyword(s):  
Exact Solutions ◽  
Structure Formation ◽  
Relativistic Cosmology

scholarly journals Breaking the cosmological background degeneracy by two-fluid perturbations in f(R) gravity

2015 ◽  
Vol 24 (07) ◽  
pp. 1550053 ◽  
Author(s):  
Amare Abebe
Keyword(s):  
General Relativity ◽  
Exact Solutions ◽  
Structure Formation ◽  
Background Level ◽  
Cosmological Perturbations ◽  
Gauge Invariant ◽  
First Order ◽  
Cosmological Background ◽  
Theories Of Gravity ◽  
Two Fluid

One of the exact solutions of f(R) theories of gravity in the presence of different forms of matter exactly mimics the ΛCDM solution of general relativity (GR) at the background level. In this work we study the evolution of scalar cosmological perturbations in the covariant and gauge-invariant formalism and show that although the background in such a model is indistinguishable from the standard ΛCDM cosmology, this degeneracy is broken at the level of first-order perturbations. This is done by predicting different rates of structure formation in ΛCDM and the f(R) model both in the complete and quasi-static regimes.

scholarly journals Lagrangian theory of structure formation in relativistic cosmology. V. Irrotational fluids

2018 ◽  
Vol 98 (4) ◽  
Author(s):  
Yong-Zhuang Li ◽  
Pierre Mourier ◽  
Thomas Buchert ◽  
David L. Wiltshire
Keyword(s):  
Structure Formation ◽  
Relativistic Cosmology
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