A special anisotropic model of the universe

1988 ◽  
Vol 20 (8) ◽  
pp. 841-845 ◽  
Author(s):  
Marcelo Samuel Berman
Keyword(s):  
Anisotropic Model ◽  
The Universe

A special anisotropic model of the universe (II)

1989 ◽  
Vol 21 (9) ◽  
pp. 967-970 ◽  
Author(s):  
Marcelo Samuel Berman ◽  
M. M. Som
Keyword(s):  
Anisotropic Model ◽  
The Universe

THE ROLE OF A CHAMELEON FIELD IN AN ANISOTROPIC UNIVERSE WITH LOGAMEDIATE AND INTERMEDIATE SCENARIOS

2010 ◽  
Vol 25 (24) ◽  
pp. 4691-4701 ◽  
Author(s):  
SHUVENDU CHAKRABORTY ◽  
UJJAL DEBNATH
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Anisotropic Universe ◽  
Anisotropic Model ◽  
Scale Factors ◽  
Slow Roll ◽  
Energy Scalar ◽  
The Universe

In this work, we consider the Universe is being filled with matter composed of a chameleon-type dark energy scalar field. Employing a particular form of potential, we discuss the field's role in the accelerating phase of the Universe for an anisotropic model using the logamediate and intermediate forms of scale factors. The natures of statefinder and slow-roll parameters are discussed diagrammatically.

scholarly journals ADIABATIC PARTICLE PRODUCTION WITH DECAYING Λ AND ANISOTROPIC UNIVERSE

2005 ◽  
Vol 14 (11) ◽  
pp. 1919-1925 ◽  
Author(s):  
SISIR BHANJA ◽  
SUBENOY CHAKRABORTY ◽  
UJJAL DEBNATH
Keyword(s):  
Cosmological Constant ◽  
Particle Production ◽  
Adiabatic Process ◽  
Anisotropic Universe ◽  
Anisotropic Model ◽  
Statefinder Parameters ◽  
Constant Energy ◽  
The Universe ◽  
Decaying Λ

Here we study an anisotropic model of the universe with constant energy per particle. A decaying cosmological constant and particle production in an adiabatic process are considered as the sources for the entropy. The statefinder parameters {r, s} are defined and their behavior are analyzed graphically in some cases.

Kantowski–Sachs cosmological solutions in the generalized teleparallel gravity via Noether symmetry

2016 ◽  
Vol 31 (15) ◽  
pp. 1650095 ◽  
Author(s):  
H. Motavalli ◽  
A. Rezaei Akbarieh ◽  
M. Nasiry
Keyword(s):  
Equation Of State ◽  
Teleparallel Gravity ◽  
Noether Symmetry ◽  
Anisotropic Model ◽  
Eos Parameter ◽  
Scale Factors ◽  
Cosmological Solutions ◽  
Frw Metric ◽  
The Universe ◽  
Friedmann Robertson Walker

We study the f(T) theory as an extension of teleparallel gravity and consider the Noether symmetry of Kantowski–Sachs (KS) anisotropic model for this theory. We specify the explicit teleparallel form of f(T) and find the corresponding exact cosmological solutions under the assumption that the Lagrangian admits the Noether symmetry. It is found that the universe experiences a power law expansion for the scale factors in the context of f(T) theory. By deriving equation of state (EOS) parameter, we show that the universe passes through the phantom and [Formula: see text]CDM theoretical scenarios. In this way, we estimate a lower limit age for the universe in excellent agreement with the value reported from recent observations. When KS model reduces to the flat Friedmann–Robertson–Walker (FRW) metric, our results are properly transformed into the corresponding values.

scholarly journals An Anisotropic Model for the Universe

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1741
Author(s):  
Morgan Le Delliou ◽  
Maksym Deliyergiyev ◽  
Antonino del Popolo
Keyword(s):  
Bianchi Type ◽  
Back Reaction ◽  
Type I ◽  
Proof Of Concept ◽  
Anisotropic Model ◽  
Hubble Diagram ◽  
Bianchi Type I ◽  
Λcdm Model ◽  
The Universe

Motivated by the back-reaction debate, and some unexplained characteristics of the CMB, we investigate the possibility of some anisotropy in the universe observed around us. To this aim, we build up a novel prediction for the Hubble law for the late universe from a Bianchi type I model, taken as proof of concept, transcribing the departure of such model from a ΛCDM model. We dicussed the redshift measurement in this universe, and finally formalized the Hubble diagram.

scholarly journals Are stellar-mass binary black hole mergers isotropically distributed?

2020 ◽  
Vol 501 (1) ◽  
pp. 970-977
Author(s):  
Richard Stiskalek ◽  
John Veitch ◽  
Chris Messenger
Keyword(s):  
Black Hole ◽  
Probability Distribution ◽  
Cosmological Model ◽  
Bayesian Model ◽  
Bayes Factor ◽  
Selection Function ◽  
Anisotropic Model ◽  
Isotropic Model ◽  
Binary Black Hole ◽  
The Universe

ABSTRACT The Advanced LIGO and Advanced Virgo gravitational wave detectors have detected a population of binary black hole mergers in their first two observing runs. For each of these events, we have been able to associate a potential sky location region represented as a probability distribution on the sky. Thus, at this point we may begin to ask the question of whether this distribution agrees with the isotropic model of the Universe, or if there is any evidence of anisotropy. We perform Bayesian model selection between an isotropic and a simple anisotropic model, taking into account the anisotropic selection function caused by the underlying antenna patterns and sensitivity of the interferometers over the sidereal day. We find an inconclusive Bayes factor of 1.3: 1, suggesting that the data from the first two observing runs are insufficient to pick a preferred model. However, the first detections were mostly poorly localized in the sky (before the Advanced Virgo joined the network), spanning large portions of the sky and hampering detection of potential anisotropy. It will be appropriate to repeat this analysis with events from the recent third LIGO observational run and a more sophisticated cosmological model.

Structures in the Universe by Exact Methods

2009 ◽  
Author(s):  
Krzysztof Bolejko ◽  
Andrzej Krasinski ◽  
Charles Hellaby ◽  
Marie-Noelle Celerier
Keyword(s):  
Exact Methods ◽  
The Universe

The Riddle of the Universe at the Close of the Nineteenth Century

2009 ◽  
Author(s):  
Ernst Heinrich Philipp August Haeckel ◽  
Joseph McCabe
Keyword(s):  
Nineteenth Century ◽  
The Universe
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