scholarly journals Weak and Strong Warm Logamediate Anisotropic Inflationary Universe Model

2019 ◽  
Author(s):  
Wajiha Javed ◽  
Iqra Nawazish ◽  
Mohsin Raza Khan ◽  
Ali Övgün
Keyword(s):  
Bianchi Identity ◽  
Scalar Potential ◽  
Chaplygin Gas ◽  
Inflationary Universe ◽  
Type I ◽  
Field Equations ◽  
Warm Inflation ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Rotationally Symmetric

This paper is given to the investigation of warm inflation using Modified Chaplygin gas in the background of locally rotationally symmetric Bianchi Identity type I. We find out the field equations and perturbations parameters such as; scalar power spectrum, scalar spectral index, scalar potential and tensor to scalar ratio under slow roll approximation. We find out these parameters in directional of Hubble parameter during the Logamediate inflationary regime in weak and strong case. These comological parameters shows that the anisotropic model is also compatible WMAP$7$ with recent observational data Planck $2018$.

scholarly journals Weak and strong warm logamediate anisotropic inflationary universe model

2020 ◽  
Vol 98 (11) ◽  
pp. 1029-1038
Author(s):  
Wajiha Javed ◽  
Iqra Nawazish ◽  
Mohsin Raza Khan ◽  
Ali Övgün
Keyword(s):  
Bianchi Type ◽  
Scalar Potential ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Inflationary Universe ◽  
Type I ◽  
Field Equations ◽  
Warm Inflation ◽  
Slow Roll ◽  
Rotationally Symmetric

In this paper we investigate a warm inflation scenario of a locally rotationally symmetric Bianchi type-I model using a background of modified Chaplygin gas. We determine the field equations and perturbations parameters, such as the scalar power spectrum, scalar spectral index, scalar potential, and tensor-to-scalar ratio under the slow roll approximation. We determine these parameters in the direction of the Hubble parameter during both the weak and strong logamediate inflationary regimes. These cosmological parameters show that the anisotropic model is compatible with WMAP 7 from the 2018 Planck observational data.

scholarly journals Tachyon Warm Intermediate and Logamediate Inflation in the Brane World Model in the Light of Planck Data

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
V. Kamali ◽  
M. R. Setare
Keyword(s):  
Scale Factor ◽  
Brane World ◽  
Inflationary Universe ◽  
Tachyon Field ◽  
World Model ◽  
Planck Data ◽  
Warm Inflation ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Two Sectors

Tachyon inflationary universe model on the brane in the context of warm inflation is studied. In slow-roll approximation and in longitudinal gauge, we find the primordial perturbation spectrums for this scenario. We also present the general expressions of the tensor-scalar ratio, scalar spectral index, and its running. We develop our model by using exponential potential; the characteristics of this model are calculated in great detail. We also study our model in the context of intermediate (where scale factor expands asa=a0exp⁡Atf) and logamediate (where the scale factor expands asa=a0exp⁡Aln⁡tν) models of inflation. In these two sectors, dissipative parameter is considered as a constant parameter and a function of tachyon field. Our model is compatible with observational data. The parameters of the model are restricted by Planck data.

scholarly journals CHAPLYGIN INFLATION IN LOOP QUANTUM COSMOLOGY

2009 ◽  
Vol 24 (22) ◽  
pp. 1763-1773 ◽  
Author(s):  
XIN ZHANG ◽  
JINGFEI ZHANG ◽  
JINGLEI CUI ◽  
LI ZHANG
Keyword(s):  
Equation Of State ◽  
Quantum Cosmology ◽  
Chaplygin Gas ◽  
Effective Theory ◽  
Loop Quantum Cosmology ◽  
Inflationary Universe ◽  
Quadratic Potential ◽  
Inflation Model ◽  
Slow Roll ◽  
Scalar Spectral Index

In this paper we discuss the inflationary universe in the context of a Chaplygin gas equation of state within the framework of the effective theory of loop quantum cosmology. Under the slow-roll approximation, we calculate the primordial perturbations for this model. We give the general expressions of the scalar spectral index, its running, and the tensor-to-scalar ratio, etc. For the chaotic inflation with a quadratic potential, using the WMAP 5-year results, we determine the parameters of the Chaplygin inflation model in loop quantum cosmology. The results are consistent with the WMAP observations.

Evolution of anisotropic cosmic models in f(R,ϕ) gravity

2018 ◽  
Vol 27 (12) ◽  
pp. 1850115 ◽  
Author(s):  
M. Zubair ◽  
Farzana Kousar ◽  
Saira Waheed
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Bianchi Type ◽  
Scalar Potential ◽  
Anisotropic Fluid ◽  
Type I ◽  
Field Equations ◽  
Eos Parameter ◽  
Free Parameters ◽  
Physical Quantities

In this paper, we will discuss cosmological models using Bianchi type I for anisotropic fluid in [Formula: see text] theory of gravity which involves scalar potential. For this purpose, we consider power law assumptions of coupling function and scalar field along with the proportionality condition of expansion and shear scalars. We choose two [Formula: see text] models and obtain exact solutions of field equations in both cases. For these constructed models, the behavior of different physical quantities like EoS parameter, self-interacting potential as well as deceleration and skewness parameters are explored and illustrated graphically for the feasible ranges of free parameters. It is concluded that anisotropic fluid approaches isotropy in later cosmic times for both models.

Reconstruction of warm Chaplygin gas inflationary models

2020 ◽  
Vol 35 (32) ◽  
pp. 2050268
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
Kazuharu Bamba ◽  
Nadeem Azhar
Keyword(s):  
Spectral Index ◽  
Effective Potential ◽  
Chaplygin Gas ◽  
Index Formula ◽  
Curvature Perturbation ◽  
Warm Inflation ◽  
Scalar Spectral Index ◽  
Dissipative Coefficient ◽  
Inflationary Parameters ◽  
Friedmann Robertson Walker

By assuming the specific Chaplygin gas model, we study the reconstruction of warm inflation model with the help of tensor-to-scalar ratio [Formula: see text] and scalar spectral index [Formula: see text]. In this regard, we take flat Friedmann–Robertson–Walker (FRW) metric and discuss the general forms of dissipative coefficient [Formula: see text] as well as effective potential [Formula: see text] for two dissipative regimes i.e., the weak and strong. We use inflationary parameters such as slow-roll parameters, power spectrum of the curvature perturbation, tensor spectrum, spectral index, scalar-to-tensor ratio and Hubble parameter to find the generalized form of dissipative coefficient and effective potential. We discuss the results of dissipative coefficient and reconstructed potential in detail for the specific choice of tensor-to-scalar ratio [Formula: see text] and scalar spectral index [Formula: see text].

The Mimetic Matter in LRS Bianchi Type-I Model

2021 ◽  
Author(s):  
Ertan Gudekli ◽  
E. Demir
Keyword(s):  
Bianchi Type ◽  
State Parameter ◽  
Relativity Theory ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Rotationally Symmetric ◽  
Bianchi Type I Universe ◽  
Expansion Of The Universe ◽  
The Universe

This paper deals with the Locally rotationally symmetric (LRS) Bianchi type-I universe model in Mimetic Gravity Theory assuming it an extended form of General Relativity Theory. It was proclaimed as a conformal transformation of the Einstein-Hilbert action from Einstein frame to Jordon frame. At the outset, we have proposed a potential function on account of clarifying the expansion of our universe by considering the general solutions of the field equations that originate from the action of the theory including the Lagrange multipliers. Lastly, after having been achieved the general equation of the state parameter ω, we discussed whether the result corresponds to some fluids illuminating the expansion of the Universe or not.

Shaft potential inspired warm inflation

2017 ◽  
Vol 14 (06) ◽  
pp. 1750088 ◽  
Author(s):  
Abdul Jawad ◽  
Amara Ilyas ◽  
Sarfraz Ahmad
Keyword(s):  
Scalar Field ◽  
Spectral Index ◽  
Power Spectra ◽  
Spectral Indices ◽  
Tensor Power ◽  
Planck Data ◽  
Warm Inflation ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Inflationary Parameters

We discuss the warm inflation in the presence of shaft potential [Formula: see text], tachyon scalar field and the generalized form of dissipative coefficient [Formula: see text]. In this respect, we investigate the inflationary parameters (slow-roll parameters, number of e-folds, scalar-tensor power spectra, spectral indices, tensor-to-scalar ratio and running of scalar spectral index) in both strong and weak dissipative regimes. It is interesting to mention that our inflationary parametric results (tensor-scalar ratio, spectral index and running of spectral) are consistent with the recent observational data such as BICEP[Formula: see text], WMAP[Formula: see text] and latest Planck data.

scholarly journals Warm inflation with non-comoving scalar field and radiation fluid

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Tiberiu Harko ◽  
Haidar Sheikhahmadi
Keyword(s):  
Scalar Field ◽  
Anisotropic Fluid ◽  
Type I ◽  
Field Equations ◽  
Warm Inflation ◽  
Inflationary Scenario ◽  
Radiation Generation ◽  
Theoretical Predictions ◽  
Field Radiation ◽  
Basic Equations

AbstractWe consider a warm inflationary scenario in which the two major fluid components of the early Universe, the scalar field and the radiation fluid, evolve with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid, expanding with a four-velocity that is a combination of the two fluid four-velocities. Due to the presence of anisotropies the overall cosmological evolution is also anisotropic. We obtain the gravitational field equations of the non-comoving scalar field–radiation mixture for a Bianchi Type I geometry. By assuming the decay of the scalar field, accompanied by a corresponding radiation generation, we formulate the basic equations of the warm inflationary model in the presence of two non-comoving components. By adopting the slow-roll approximation the theoretical predictions of the warm inflationary scenario with non-comoving scalar field and radiation fluid are compared in detail with the observational data obtained by the Planck satellite in both weak dissipation and strong dissipation limits, and constraints on the free parameters of the model are obtained. The functional forms of the scalar field potentials compatible with the non-comoving nature of warm inflation are also obtained.

Dynamics of single-field inflation in the framework of holographic f(T) gravity

2018 ◽  
Vol 15 (10) ◽  
pp. 1850167 ◽  
Author(s):  
Surajit Chattopadhyay ◽  
Antonio Pasqua ◽  
Irina Radinschi ◽  
Aroonkumar Beesham
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Energy Density ◽  
Linear Form ◽  
Index Formula ◽  
Inflationary Universe ◽  
Ricci Dark Energy ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Single Field

In the work reported in the present paper, we have considered the inflationary dynamics inspired by holographic Ricci dark energy (HRDE) with the energy density [Formula: see text] in the framework of [Formula: see text] gravity. We have considered a [Formula: see text]-gravity model in linear form, which is sourced by a canonical scalar field due to the HRDE. We have investigated an inflationary Universe in this framework through slow-roll formalism. We also studied the scalar spectral index [Formula: see text] and tensor-to-scalar ratio [Formula: see text], which have come out to be in agreement with WMAP[Formula: see text]BAO[Formula: see text][Formula: see text] and Planck 2015 data.

Power law inflation with anisotropic fluid in Lyra’s manifold

2017 ◽  
Vol 95 (8) ◽  
pp. 748-752 ◽  
Author(s):  
S. Surendra Singh ◽  
Y. Bembem Devi ◽  
M. Saratchandra Singh
Keyword(s):  
Power Law ◽  
Bianchi Type ◽  
Anisotropic Fluid ◽  
Type I ◽  
Field Equations ◽  
Volumetric Expansion ◽  
Lyra’S Manifold ◽  
Rotationally Symmetric ◽  
Age Of The Universe ◽  
The Universe

Field equations of the locally rotationally symmetric (LRS) Bianchi type-I metric with anisotropic fluid are constructed within the framework of Lyra’s manifold. Power-law volumetric expansion is used to obtain exact solutions of the models for constant and time-dependent displacement field. We discuss the asymptotic behaviors of the derived models, anisotropic behavior of the fluid, expansion parameter, and the evolution of the model with the age of the universe.

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