Superposition of FLRW universes

Heydarzade, Yaghoub
Tekin, Bayram
We show that (1) the Einstein field equations with a perfect fluid source admit a nonlinear superposition of two distinct homogenous Friedman-Lemaitre-Robertson-Walker (FLRW) metrics as a solution, (2) the superposed solution is an inhomogeneous geometry in general, (3) it reduces to a homogeneous one in the two asymptotes which are the early and the late stages of the universe as described by two different FLRW metrics, (4) the solution possesses a scale factor inversion symmetry and (5) the solution implies two kinds of topology changes: one during the time evolution of the superposed universe and the other occurring in the asymptotic region of space.


Kundt solutions of minimal massive 3D gravity
Deger, Nihat Sadik; Sarıoğlu, Bahtiyar Özgür (AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA, 2015-11-04)
We construct Kundt solutions of minimal massive gravity theory and show that, similar to topologically massive gravity (TMG), most of them are constant scalar invariant (CSI) spacetimes that correspond to deformations of round and warped (A) dS. We also find an explicit non-CSI Kundt solution at the merger point. Finally, we give their algebraic classification with respect to the traceless Ricci tensor (Segre classification) and show that their Segre types match with the types of their counterparts in TMG.
BAYIN, SS; COOPERSTOCK, FI; FARAONI, V (American Astronomical Society, 1994-06-20)
We explore the possibility of describing our universe with a singularity-free, closed, spatially homogeneous and isotropic cosmological model, using only general relativity and a suitable equation of state which produces an inflationary era. A phase transition to a radiation-dominated era occurs as a consequence of boundary conditions expressing the assumption that the temperature cannot exceed the Planck value. We find that over a broad range of initial conditions, the predicted value of the Hubble paramet...
Topological black holes and momentum four-vector
Pirinccioglu, Nurettin; Binbay, Figen; AÇIKGÖZ, İRFAN; Aydogdu, Oktay (World Scientific Pub Co Pte Lt, 2007-07-30)
We consider the energy momentum definition of the Moller in both general relativity and teleparallel gravity to evaluate the energy distribution (due to both matter and fields including gravitation) associated with the topological black holes with a conformally coupled scalar field. Our results show that the energy depends on the mass M and charge Q of the black holes and cosmological constant Lambda. In some special limits, the expression of the energy reduces to the energy of the well-known spacetimes. Th...
Conserved Killing charges of quadratic curvature gravity theories in arbitrary backgrounds
Devecioglu, Deniz Olgu; Sarıoğlu, Bahtiyar Özgür (2011-01-24)
We extend the Abbott-Deser-Tekin procedure of defining conserved quantities of asymptotically constant-curvature spacetimes, and give an analogous expression for the conserved charges of geometries that are solutions of quadratic curvature gravity models in generic D dimensions and that have arbitrary asymptotes possessing at least one Killing isometry. We show that the resulting charge expression correctly reduces to its counterpart when the background is taken to be a space of constant curvature and, more...
Anti-de Sitter-Wave Solutions of Higher Derivative Theories
GÜRSES, METİN; Hervik, Sigbjorn; Sisman, Tahsin Cagri; Tekin, Bayram (American Physical Society (APS), 2013-09-05)
We show that the recently found anti-de Sitter (AdS)-plane and AdS-spherical wave solutions of quadratic curvature gravity also solve the most general higher derivative theory in D dimensions. More generally, we show that the field equations of such theories reduce to an equation linear in the Ricci tensor for Kerr-Schild spacetimes having type-N Weyl and type-N traceless Ricci tensors.
Citation Formats
M. GÜRSES, Y. Heydarzade, and B. Tekin, “Superposition of FLRW universes,” JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, pp. 0–0, 2020, Accessed: 00, 2020. [Online]. Available: