Academia.eduAcademia.edu

Outline

Title
Abstract
Key Takeaways
Figures
Introduction
Statistical Analysis of the Parameter
State Finder Analysis
Conclusion
References
All Topics
Physics
Astrophysics

Curvature dominance dark energy model in f(R)-gravity

Profile image of HARSHNA BALHARAHARSHNA BALHARA

Indian Journal of Physics

https://doi.org/10.1007/S12648-023-02674-3
visibility

…

description

9 pages

link

1 file

Abstract

We have probed a cosmological model in f (R)-gravity, which is a cubic equation in scalar curvature R. The terms arise due to nonlinear f (R) function are treated as energy due to curvature inspired geometry. As a result, we find accelerating expansion in the universe, which creates an anti-gravitating negative pressure in it. Some of the physical parameters are solved using numerical methods. The evolution of the model are examined by the latest observational Hubble data (46data points) and Pantheon data (the latest compilation of SNIa with 40 binned in the redshift range 0.014 z 1.62). Some important features of the model have been discussed by analyzing the plots of various dynamical parameters. The plots of deceleration parameter q and the Hubble parameter H describe the accelerating expansion in the evolution of the Universe at the present epoch. The transition from deceleration to acceleration for our model is obtained at redshift ztr 0.694069, which is in good agreement with ΛCDM. We have also carried out state finder analysis for our model. The analysis of specific features of the model confirms that our model is consistent with ΛCDM in late times.

Key takeaways
sparkles

AI

  1. The model demonstrates accelerating universe expansion consistent with ΛCDM, with a transition redshift z_tr at 0.694069.
  2. Utilizing 46 Hubble data points and 40 Pantheon supernova observations validates the proposed f(R) model.
  3. The deceleration parameter q is found to be -0.55, indicating current acceleration in the universe.
  4. The model incorporates a cubic f(R) function, specifically f(R) = R + αR² + βR³, to describe curvature effects.
  5. State finder analysis confirms the model's proximity to ΛCDM, supporting its observational validity.
Figures (5)
8rG 3H? as peo = 1.88 x 10~7°h2 gm/cm?, where 0.5 < ho < 1. EoS-parameter for curvature inspired pressure and density may be defined as w, = 2 re Since pco is negligibly small, so we shall make certain corrections aS Pmo = Qmo for further calculations. If we put the present values of H and its derivatives in Eqns. (7),(8) and (11), we get the following relations amongst the parameters a, 8,OQmo and wxo as: The energy parameter 22, is defined as 0, = = ™, ™ where pc = is the critical density. Its present value is given In Fig. 2, we see that the deceleration parameter q is negative at present. This shows that we are living in an accelerating universe. The red shift transition is shifted from positive to negative values at z:, ~ 0.694069, which shows that the universe transforms from decelerating mode in the past to accelerating mode in late times. The jerk parameter approaches to ACDM because j > 1 as z > 0. The present values of the deceleration parameter gg = —0.55 and jerk parameter j9 = 1 of the obtained model is consistent with ACDM model. Planck’s latest survey [29] provides us the present value of Hubble constant Ho ~ 68 Mpc/Km/sec ~ 0.07Gyr~*. From these values, we can estimate the present values of first and second derivatives of Hubble parameter as (44)9 = 0.0315 and (2 H)) — 0.48825.
8rG 3H? as peo = 1.88 x 10~7°h2 gm/cm?, where 0.5 < ho < 1. EoS-parameter for curvature inspired pressure and density may be defined as w, = 2 re Since pco is negligibly small, so we shall make certain corrections aS Pmo = Qmo for further calculations. If we put the present values of H and its derivatives in Eqns. (7),(8) and (11), we get the following relations amongst the parameters a, 8,OQmo and wxo as: The energy parameter 22, is defined as 0, = = ™, ™ where pc = is the critical density. Its present value is given In Fig. 2, we see that the deceleration parameter q is negative at present. This shows that we are living in an accelerating universe. The red shift transition is shifted from positive to negative values at z:, ~ 0.694069, which shows that the universe transforms from decelerating mode in the past to accelerating mode in late times. The jerk parameter approaches to ACDM because j > 1 as z > 0. The present values of the deceleration parameter gg = —0.55 and jerk parameter j9 = 1 of the obtained model is consistent with ACDM model. Planck’s latest survey [29] provides us the present value of Hubble constant Ho ~ 68 Mpc/Km/sec ~ 0.07Gyr~*. From these values, we can estimate the present values of first and second derivatives of Hubble parameter as (44)9 = 0.0315 and (2 H)) — 0.48825.
The minimum value of Chi-square is found to be x?,;,, = 19.348 for wxo = —0.44 and Q0 = 0.25. From the eqns. (18) and (19), we get a = 1.0027 and 6 = —5074.44. The process is shown in the Fig. 2. in which blue dot is the estimated point (—0.44, 0.25, 19.348) for minimum Chi-square. FIG. 2. Blue and Red dots indicate the present values of Qm0 and wo of our model in the Chi-square and Region plots respectively.
The minimum value of Chi-square is found to be x?,;,, = 19.348 for wxo = —0.44 and Q0 = 0.25. From the eqns. (18) and (19), we get a = 1.0027 and 6 = —5074.44. The process is shown in the Fig. 2. in which blue dot is the estimated point (—0.44, 0.25, 19.348) for minimum Chi-square. FIG. 2. Blue and Red dots indicate the present values of Qm0 and wo of our model in the Chi-square and Region plots respectively.
We have presented the Hubble Error and the distance modulus plots versus red shift in Fig.2. Our plots are matching with graph prepared on the basis of ACDM model, which shows that these are in a good agreement with our theoretical and observed results. FIG. 3. The blue color error bars of observational data H(z) and SNJa in the plots indicate the deviations of the model from ACDM. Red and black lines represent our obtained model and the ACDM respectively.
We have presented the Hubble Error and the distance modulus plots versus red shift in Fig.2. Our plots are matching with graph prepared on the basis of ACDM model, which shows that these are in a good agreement with our theoretical and observed results. FIG. 3. The blue color error bars of observational data H(z) and SNJa in the plots indicate the deviations of the model from ACDM. Red and black lines represent our obtained model and the ACDM respectively.
dH The numerical values of H, G- and ae for redshifts z are calculated from (12) and then using (11), we evaluat matter density p,,. The related plot of pm ~ z can be seen in Fig. 4. As per observations, the value of matter energ: Equation of state parameter w, for curvature dominated energy is defined as w, = 7*, where pz and px are Pk given by Eqns. (7) and (8). In wy ~ z plot, wz is negative and is equal to —0.44 at present (see Fig. 3). The curvature dominated pressure p;, becomes negative from positive at the redshift transition z ~ 1.65. Therefore, we say that the accelerated dark energy model is developed due to negative pressure.
dH The numerical values of H, G- and ae for redshifts z are calculated from (12) and then using (11), we evaluat matter density p,,. The related plot of pm ~ z can be seen in Fig. 4. As per observations, the value of matter energ: Equation of state parameter w, for curvature dominated energy is defined as w, = 7*, where pz and px are Pk given by Eqns. (7) and (8). In wy ~ z plot, wz is negative and is equal to —0.44 at present (see Fig. 3). The curvature dominated pressure p;, becomes negative from positive at the redshift transition z ~ 1.65. Therefore, we say that the accelerated dark energy model is developed due to negative pressure.
FIG. 5. The plots of s — r and q — r for state finder analysis. In recent years, various observations have certified that our universe is accelerating at the present epoch, whicl caused a huge list of various DE-models have been proposed so far. Based on EoS-parameter wae for dark energy the most eminent models ACDM (w¢e=1), QCDM (wae > —1/3 < —1), KCDM (wae is negative and variable) Chaplygin gas energy model and Brain world model etc. are proposed so far. The references related to these model can be seen in [32, 33]. In the year 2003, Sahni et al. [25, 26] proposed an analysis to examine the different categor of established dark energy models. This analysis is based on deceleration parameter q and jerk parameter r a defined earlier. They have introduced a new parameter s, which is defined as s = Cant q # 1/2, and focused o1 two-dimensional s ~ r and q ~ r plots. We have presented the plots for our model (see Fig. 5). It is interesting t see that our model approaches to ACDM from both ends i.e. from Chaplygin gas to ACDM and from quintessence t: ACDM in s~r plot. Ing~r plot, our model passes nearby ACDM. So we can say that our model lies near ACDM and it fits well on observational ground.
FIG. 5. The plots of s — r and q — r for state finder analysis. In recent years, various observations have certified that our universe is accelerating at the present epoch, whicl caused a huge list of various DE-models have been proposed so far. Based on EoS-parameter wae for dark energy the most eminent models ACDM (w¢e=1), QCDM (wae > —1/3 < —1), KCDM (wae is negative and variable) Chaplygin gas energy model and Brain world model etc. are proposed so far. The references related to these model can be seen in [32, 33]. In the year 2003, Sahni et al. [25, 26] proposed an analysis to examine the different categor of established dark energy models. This analysis is based on deceleration parameter q and jerk parameter r a defined earlier. They have introduced a new parameter s, which is defined as s = Cant q # 1/2, and focused o1 two-dimensional s ~ r and q ~ r plots. We have presented the plots for our model (see Fig. 5). It is interesting t see that our model approaches to ACDM from both ends i.e. from Chaplygin gas to ACDM and from quintessence t: ACDM in s~r plot. Ing~r plot, our model passes nearby ACDM. So we can say that our model lies near ACDM and it fits well on observational ground.

Related papers

Note on the equation of state of geometric dark energy in <span class="aps-inline-formula"><math display="inline"><mrow><mi>f</mi><mo stretchy="false">(</mo><mi>R</mi><mo stretchy="false">)</mo></mrow></math></span> gravity
Leonardo Patiño

Physical Review D, 2014

We focus on the analysis of three inequivalent equations of state of geometric dark energy in f (R) cosmology that have been considered in the past and discuss their differences, advantages and drawbacks.

View PDFchevron_right
Accelerating Universe, Dark Energy and Exponential f (T ) Gravity
Salim Shekh

In this paper, we inspect the evolution of the dark energy parameter for spatially homogeneous and anisotropic Bianchi type-I universe within the framework of modified theory of gravity, the so called f (T ) gravity, using a suitable physical assumption and applying the law of variation of Hubble’s parameter that yields the constant value of deceleration parameter. In this model, the equation of state parameter (w) is found to be time dependent and its existing range is consistent with the conjectural experiments of Wilkinson Microwave Anisotropic Probe (WMAP) satellite experiment, type Ia supernovae, (with CMBR anisotropy) and galaxy clustering statistics. The physical behavior of these models has been discussed using some physical quantities. Also, a function of torsion scalar for the Universe is evaluated.

View PDFchevron_right
Dark Energy Cosmology: The Equivalent Description via Different Theoretical Models and Cosmography Tests -Kazuharu Bamba - A Comparative Analysis of Theoretical Frameworks, Observational Constraints, and the Role of Scalar Fields, Modified Gravity Theories, & Future Singularities -RARE Text!
Alexander T H E L I B R A R Y C A T O F : The New Alexandria Library of Texas 🇨🇱 Ft Also DeepAncientThought

The New Alexandria Library of Texas

This very fascinating obscure paper we investigate the nature of dark energy within the framework of cosmology, focusing on different theoretical models and their equivalence in explaining the accelerated expansion of the universe. We explore the ΛCDM model, the standard model of cosmology, as well as alternative models such as scalar field theories, including quintessence, phantom energy, and tachyon fields, alongside modified gravity theories like F(R) and f(T) gravity. The paper provides a detailed comparison of these models through cosmographic tests, using observational data from Type Ia supernovae, Baryon Acoustic Oscillations, and Cosmic Microwave Background radiation to constrain their validity. In addition, we delve into the concept of future singularities, including type I, II, III, and IV singularities, as they relate to the fate of the universe. We also examine the role of holographic dark energy and the generalized Chaplygin gas model as potential candidates for describing the universe's dark energy content. Through the analysis of these models, we aim to provide a comprehensive understanding of the dynamics of dark energy and its implications for the evolution and ultimate fate of the cosmos. By bridging theoretical frameworks with observational constraints, this study contributes to advancing our knowledge of the mysterious force driving the universe's accelerated expansion. Here is a brief summary for each chapter in the paper "Dark Energy Cosmology: The Equivalent Description via Different Theoretical Models and Cosmography Tests": I. Introduction (6) This section introduces the fundamental problem of dark energy in cosmology, the accelerated expansion of the universe, and provides an overview of various theoretical models and cosmographic tests. It sets the stage for exploring how different models attempt to explain dark energy and its implications for the universe's evolution. II. The Λ Cold Dark Matter (ΛCDM) Model (10) This chapter outlines the standard ΛCDM model, which includes the cosmological constant (Λ) as a form of dark energy. It discusses observational tests that validate the model, such as Type Ia Supernovae (SNe Ia), Baryon Acoustic Oscillations (BAO), and Cosmic Microwave Background (CMB) radiation, which support the ΛCDM framework. III. Cosmology of Dark Fluid Universe (17) This chapter explores alternative models of dark energy, including the concept of a "dark fluid" that combines dark energy and dark matter into a unified framework. It covers equations of state (EoS), finite-time future singularities, and the behavior of various models, such as the Generalized Chaplygin Gas (GCG) and coupled dark energy with dark matter, as well as phantom scenarios, including the Little Rip and Pseudo-Rip cosmologies. IV. Scalar Field Theory as Dark Energy of the Universe (46) Scalar field theories are examined as possible explanations for dark energy. This chapter discusses the equivalence between fluid descriptions and scalar field theories, presenting various cosmological models such as the ΛCDM, Quintessence, Phantom, and unified inflationary models. It also explores scalar fields crossing the phantom divide and their implications for cosmic acceleration. V. Tachyon Scalar Field Theory (56) This section focuses on tachyon scalar fields as an alternative form of dark energy. It explores how tachyon fields can be incorporated into cosmological models to explain the accelerated expansion of the universe and examines their relationship to other scalar field models. VI. Multiple Scalar Field Theories (59) This chapter delves into models with multiple scalar fields, both standard and new types of multi-scalar field theories. It provides an overview of two-scalar field theories and explores the complexities introduced by models with n (≥ 2) scalar fields, which could offer more flexible explanations for dark energy. VII. Holographic Dark Energy (70) The concept of holographic dark energy is introduced in this chapter, which links dark energy to the holographic principle. It includes models of holographic dark energy, generalized forms, and the role of the Hubble entropy in cosmological evolution. VIII. Accelerating Cosmology in F(R) Gravity (78) This section examines F(R) gravity, a modified theory of gravity that includes a general function of the Ricci scalar R. It discusses the reconstruction methods of F(R) gravity, its relation to scalar field theories, and different cosmological scenarios such as the ΛCDM, quintessence, and phantom models. IX. f(T) Gravity (94) This chapter focuses on f(T) gravity, an extension of general relativity based on torsion instead of curvature. It discusses the basic formalism, the reconstruction of f(T) models, and the implications of finite-time future singularities within this framework. It also explores thermodynamic aspects of f(T) gravity. X. Testing Dark Energy and Alternative Gravity by Cosmography: Generalities (104) This chapter presents cosmographic tests as a method for testing dark energy models and alternative gravity theories. It introduces general principles and techniques used to constrain cosmological models through observational data and the expansion history of the universe. XI. An Example: Testing F(R) Gravity by Cosmography (112) A practical example of using cosmographic tests to evaluate F(R) gravity models is provided here. The chapter discusses how different F(R) models, including the CPL model, the ΛCDM case, and constant EoS models, are tested using observational data. XII. Theoretical Constraints on the Model Parameters (125) This chapter provides a detailed analysis of the theoretical constraints on model parameters, including the double power law Lagrangian and the Hu-Sawicki model. These constraints help refine the accuracy of dark energy models and assess their viability in explaining cosmic acceleration. XIII. Constraints Coming from Observational Data (130) This section focuses on the observational data used to test and constrain dark energy models. It reviews the latest measurements from supernovae, CMB, BAO, and other cosmological probes to establish the validity of various dark energy theories. XIV. Conclusion (137) The conclusion summarizes the main findings of the paper, highlighting the strengths and weaknesses of the different theoretical models of dark energy and the role of cosmographic tests in improving our understanding of the universe's accelerated expansion. It suggests potential directions for future research. Acknowledgments (139) This section acknowledges the contributions and support received from various researchers and funding bodies involved in the study. References (140) A comprehensive list of references is provided, detailing the sources and works cited throughout the paper. This summary gives a concise overview of the chapters and their key topics. Let me know if you'd like further details! Tags dark energy, cosmology, ΛCDM model, dark matter, accelerated expansion, cosmic acceleration, cosmographic tests, observational data, supernovae, Type Ia Supernovae, Baryon Acoustic Oscillations, Cosmic Microwave Background, scalar field theory, quintessence, phantom energy, coupled dark energy, Generalized Chaplygin Gas, GCG model, future singularities, finite-time singularities, inhomogeneous universe, dark fluid universe, dark energy equation of state, cosmological constant, universe evolution, cosmic fate, cosmological parameters, observational constraints, cosmological surveys, inflation, unified inflationary models, tachyon field, multiple scalar fields, F(R) gravity, f(T) gravity, modified gravity theories, torsion gravity, dark fluid, cosmological models, phantom phase, Little Rip, Pseudo-Rip cosmology, cosmic structure, future singularities, scalar field reconstruction, cosmology of dark energy, dark energy models, alternative gravity theories, scalar-tensor theories, cosmological reconstruction, holographic dark energy, holographic principle, dark energy reconstruction, modified theories of gravity, curvature, Ricci scalar, torsion, f(T) models, cosmic history, type I singularities, type II singularities, type III singularities, type IV singularities, cosmological observations, parameter fitting, dark energy density, universe expansion rate, cosmological probes, late-time acceleration, accelerated universe, cosmic history tests, energy conditions, model-independent tests, supernova constraints, large-scale structure, cosmic observations, dynamical dark energy, cosmological evolution, cosmic destiny, observational cosmology, dark matter interaction, dark energy theories, scalar-tensor theory equivalence, general relativity, gravitational theories, cosmological inflation, dark energy densities, gravitational lensing, cosmic surveys, dark energy equation of state (EoS), phantom divide, dark energy models, observational constraints, cosmology tests, equation of state, cosmological constant value, redshift surveys, dark energy components, cosmological dynamics, future cosmological probes, cosmic parameters, dark energy constraints, modified gravitational models, cosmic acceleration models, cosmic microwave background anisotropies, perturbation theory, universe parameter constraints, cosmological theory comparisons, structure formation, cosmological tests, exotic matter, cosmic thermodynamics, future cosmic fate, future singularity models, universe's fate, quantum field theories, dark energy interpretation, cosmological data, scalar fields, field theory models, cosmic theory predictions, dark energy density fluctuations, cosmic acceleration measurements, energy content of the universe, unified cosmological models, cosmological limits, gravitational wave signals, testing dark energy, dark energy inflation, quantum cosmology, cosmology of the future, gravity theories, quantum perturbations, large-scale structure measurements, cosmic structure formation, cosmic fluid equations, future testing of cosmology, ...

View PDFchevron_right
DARK ENERGY COSMOLOGICAL MODEL IN A MODIFIED THEORY OF GRAVITY
Salim Shekh

The dark energy model with equation of state (EoS) parameter is derived for a non-static plane symmetric space-time filled with a perfect fluid source in the framework of f (R, T) gravity (Harko et al., arXiv: 1104.2669v2 [gr-qc], 2011). To obtain a determinate solution, a special form of deceleration parameter (DP) is used. We have assumed that the relation between metric potentials and the EoS parameter is proportional to the skewness parameter. It is observed that the EoS parameter, and the skewness parameter in the model turn out to be functions of cosmic time. Some physical and kinematical properties of the model are also discussed.

View PDFchevron_right
Dynamics of a parametrized dark energy model in f(R,T) gravity
j jena

Annals of Physics

We investigate a flat FLRW-model in f (R, T)-gravity, which includes the quadratic variation in scalar curvature R and the linear term of the trace of the stress-energy tensor T. In turn, we establish the model has the behaviour of the late time Universe, which is accelerated expanding and ends up in a big rip. Using the parametrization of scale factor a(t), we propose a model, which begins with point-type singularity, i.e., the model starts with a point of zero volume, infinite energy density and infinite temperature. The model's behaviour is accelerated expanding at present and ΛCDM in late times. Finally, the proposed model behaves like a quintessence dark energy model in the present time and is consistent with standard cosmology ΛCDM in late times.

View PDFchevron_right
Cosmology in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>f</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>Q</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math> gravity: A unified dynamical systems analysis of the background and perturbations
JIbitesh Dutta

Physical review, 2023

View PDFchevron_right
Cosmographic Analysis of Dark Energy
Matt Visser

Dark Matter in Astrophysics and Particle Physics - Proceedings of the 7th International Heidelberg Conference on Dark 2009, 2010

http://msor.victoria.ac.nz/ The Hubble relation between distance and redshift is a purely cosmographic relation that depends only on the symmetries of a FLRW spacetime, but does not intrinsically make any dynamical assumptions. This suggests that it should be possible to estimate the parameters defining the Hubble relation without making any dynamical assumptions. To test this idea, we perform a number of interrelated cosmographic fits to the legacy05 and gold06 supernova datasets, paying careful attention to the systematic uncertainties. Based on this supernova data, the "preponderance of evidence" certainly suggests an accelerating universe. However we would argue that (unless one uses additional dynamical and observational information, and makes additional theoretical assumptions) this conclusion is not currently supported "beyond reasonable doubt". As part of the analysis we develop two particularly transparent graphical representations of the redshift-distance relation-representations in which acceleration versus deceleration reduces to the question of whether the relevant graph slopes up or down.

View PDFchevron_right
Nonlinear Evolution of F (R) Cosmologies. II. Power Spectrum
Marcos Lima

Physical Review D, 2008

We carry out a suite of cosmological simulations of modified action f(R) models where cosmic acceleration arises from an alteration of gravity instead of dark energy. These models introduce an extra scalar degree of freedom which enhances the force of gravity below the inverse ...

View PDFchevron_right
Oscillations of the F(R) dark energy in the accelerating universe
Lorenzo Sebastiani

Oscillations of the F(R) dark energy around the phantom divide line, ωDE=−1, both during the matter era and also in the de Sitter epoch are investigated. The analysis during the de Sitter epoch is revisited by expanding the modified equations of motion around the de Sitter solution. Then, during the matter epoch, the time dependence of the dark energy perturbations is discussed by using two different local expansions. For high values of the red shift, the matter epoch is a stable point of the theory, giving the possibility to expand the F(R)-functions in terms of the dark energy perturbations. In the late-time matter era, the realistic case is considered where dark energy tends to a constant. The results obtained are confirmed by precise numerical computation on a specific model of exponential gravity. A novel and very detailed discussion is provided on the critical points in the matter era and on the relation of the oscillations with possible singularities.

View PDFchevron_right
Cosmology in presence of dark energy in an emergent gravity scenario
Goutam Manna

We obtain the analogues of the Friedman equations in an emergent gravity scenario in the presence of dark energy. The background metric is taken to be Friedman-Lemaitre-Robertson-Walker (FLRW). We show that if $\dot\phi ^{2}$ is the dark energy density (in units of the critical density) then (a) for total energy density greater than the pressure (non-relativistic scenario, matter domination) the deceleration parameter $q(t)\approx\frac {1}{2} [1 + 27 \dot\phi ^{2}+...] &gt; \frac{1}{2}$ (b) for total energy density equal to 3 times the pressure (relativistic case, radiation domination), the deceleration parameter $q(t)\approx 1 + 18\dot\phi ^{2} +... &gt; 1$ and (c) for total energy density equal to the negative of the pressure (dark energy scenario), the deceleration parameter $q(t)&lt; -1$. Our results indicate that many aspects of standard cosmology can be accommodated with the presence of dark energy right from the beginning of the universe where the time parameter $t\equiv \fra...

View PDFchevron_right

References (33)

  1. S. Perlmutter et al., Astrophys. J., 517, 5 (1999)
  2. A. G. Riess et al., Astron. J., 116, 1009 (1998)
  3. J. P. Ostriker and P. J. Steinhardt, Nature 377, 600 (1995), and references therein.
  4. M. S. Turner, G. Steigman, and L. Krauss, Phys. Rev. Lett., 52, 2090 (1984)
  5. D. N. Spergel et al., [WMAP Collaboration], Astrophys. J. Suppl. Ser., 170, (2007) 377
  6. M. Tegmark et al., [SDSS Collaboration], Phys. Rev. D, 69 , 103501 (2004)
  7. E. J. Copeland, M. Sami and S. Tsujikawa, Int. J. Mod. Phys. D, 15, 1753 (2006)
  8. O. Gron and S. Hervik, Einstien's General Theory of Relativity With Modern Application in Cosmology, (New York: Springer) (2007)
  9. K. Abazajian et al., [SDSS Collaboration], Astron. J., 128, 502 (2004)
  10. V. Sahni and A. A. Starobinsky, Int. J. Mod. Phys. D, 9, 373 (2000)
  11. S. Weinberg, Rev. Mod. Phys. 61, 1 ( 1989)
  12. P. Steinhardt, L. Wang and I. Zlatev, Phys. Rev. D, 59, 123504 (1999)
  13. V. B. Johri, Phys. Rev. D, 63 103504 (2001)
  14. S. Nojiri and S. D. Odintsov, Phys. Rev. D, 68 123512 (2003)
  15. A. A. Starobinsky, JETP Lett., 86 157 (2007)
  16. T. P. Sotiriou and S. Liberati, J. Phys. Conf. Ser., 68 012022 (2007)
  17. T. P. Sotiriou and S. Liberati, Annals Phys., 322 935 (2007)
  18. S. K. Srivastava and Phys. Lett, B, 648 (2007) 119 (2007)
  19. A. Mukherjee and N. Banerjee, Astrophys. Space Sci., 352 893 (2014)
  20. G. C. Samantha and N. Godani, Ind. J. Phys., 94 1303 (2020)
  21. Ciprian A. Sporea, arXiv:1403.3852v2 [gr-qc] (2014)
  22. M. Mali and S. Shankaranarayanan, Nuclear Phys. B, 937, 422 (2018)
  23. S. Capozziello, Int. J. Mod. Phys. D, 11, 483 (2002)
  24. Jonathan D. Evans, Lisa M. H. Hall, and Philippe Caillol, Phys. Rev. D, 77, 083514 (2008)
  25. J. D. Barrow and S. Cotsakis, Phys. Lett. B, 214 515518, (1988)
  26. P. A. R. Ade et al., (Planck 2015 Collaboration), A. A., 594 A20 (2016)
  27. J. D. Barrow and S. Cotsakis, Phys. Lett. B, 214 515 (1988)
  28. P. Biswas, P. Roy and R. Biswas, arXiv: 1908.00408 [gr-qc] (2019)
  29. D. M. Scolnic et al., Astrophys. J, 859 101 (2018)
  30. P. A. R. Ade, et al., Planck Λ Collaboration, Astron. Astrophys., 594 A13 (2016)
  31. N. Suzuki et al., Astrophys. J., 746 (2012) 85
  32. V. Sahni et al., JETP Lett., 77 201 (2003)
  33. U. Alam et al., Mon. Not. Roy. Astron. Soc., 344 1057 (2003)

Related papers

Curvature dominance DE-model in $f(R)$-gravity
HARSHNA BALHARA

2022

We have probed a cosmological model in f (R)-gravity, which is a cubic equation in scalar curvature R. The terms arise due to nonlinear f (R) function are treated as energy due to curvature inspired geometry. As a result, we find accelerating expansion in the universe, which creates an anti-gravitating negative pressure in it. Some of the physical parameters are solved using numerical methods. The evolution of the model are examined by the latest observational Hubble data (46data points) and Pantheon data (the latest compilation of SNIa with 40 binned in the redshift range 0.014 z 1.62). Some important features of the model have been discussed by analyzing the plots of various dynamical parameters. The plots of deceleration parameter q and the Hubble parameter H describe the accelerating expansion in the evolution of the Universe at the present epoch. The transition from deceleration to acceleration for our model is obtained at redshift ztr 0.694069, which is in good agreement with ΛCDM. We have also carried out state finder analysis for our model. The analysis of specific features of the model confirms that our model is consistent with ΛCDM in late times.

View PDFchevron_right
A constrained cosmological model in f(R,Lm) gravity
HARSHNA BALHARA

New Astronomy

In this article, we study the expanding nature of universe in the contest of f (R, Lm) gravity theory, here R represents the Ricci scalar and Lm is the matter Lagrangian density. With a specific form of f (R, Lm), we obtain the field equations for flat FLRW metric. We parametrize the deceleration parameter in terms of the Hubble parameter and from here we find four free parameters, which are constraints and estimated by using H(z), P antheon, and their joint data sets. Further, we investigate the evolution of the deceleration parameter which depicts a transition from the deceleration to acceleration phases of the universe. The evolution behaviour of energy density, pressure, and EoS parameters shows that the present model is an accelerated quintessence dark energy model. To compare our model with the ΛCDM model we use some of the diagnostic techniques. Thus, we find that our model in f (R, Lm) gravity supports the recent standard observational studies and delineates the late-time cosmic acceleration.

View PDFchevron_right
Evaluation of cosmological models in f(R,T) gravity in different dark energy scenario
Anirudh Pradhan

New Astronomy, 2022

In present paper, we search the existence of dark energy scalar field models within in f (R, T) gravity theory established by Harko et al. (Phys. Rev. D 84, 024020, 2011) in a flat FRW universe. The correspondence between scalar field models have been examined by employing new generalized dynamical cosmological term Λ(t). In this regards, the best fit observational values of parameters from three distinct sets data are applied. To decide the solution to field equations, a scale factor a = (sinh(βt)) 1/n has been considered, where β & n are constants. Here, we employ the recent ensues (H 0 = 69.2 and q 0 = −0.52) from (OHD+JLA) observation (Yu et al., Astrophys. J. 856, 3, 2018). Through the numerical estimation and graphical assessing of various cosmological parameters, it has been experienced that findings are comparable with kinematics and physical properties of universe and compatible with recent cosmological ensues. The dynamics and potentials of scalar fields are clarified in FRW scenario in the present model. Potentials reconstruction is highly reasonable and shows a periodic establishment and in agreement with latest observations.

View PDFchevron_right
Cosmological data analysis of<i>f</i>(<i>R</i>) gravity models
Zahara Girones

Journal of Cosmology and Astroparticle Physics, 2010

A class of well-behaved modified gravity models with long enough matter domination epoch and a late-time accelerated expansion is confronted with SNIa, CMB, SDSS, BAO and H(z) galaxy ages data, as well as current measurements of the linear growth of structure. We show that the combination of geometrical probes and growth data exploited here allows to rule out f (R) gravity models, in particular, the logarithmic of curvature model. We also apply solar system tests to the models in agreement with the cosmological data. We find that the exponential of the inverse of the curvature model satisfies all the observational tests considered and we derive the allowed range of parameters. Current data still allows for small deviations of Einstein gravity. Future, high precision growth data, in combination with expansion history data, will be able to distinguish tiny modifications of standard gravity from the ΛCDM model.

View PDFchevron_right
Dark energy nature in logarithmic f(R,T) cosmology
Dinesh Chandra Maurya, Jagat Singh

International Journal of Geometric Methods in Modern Physics

This research paper is an investigation of dark energy nature of logarithmic [Formula: see text]-gravity cosmology in a flat FLRW space–time universe. We have derived modified Einstein’s field equations for the function [Formula: see text] where [Formula: see text] is the Ricci scalar curvature, [Formula: see text] is the trace of the stress energy momentum tensor, and [Formula: see text] is a model parameter. We have solved field equations in the form of two fluid scenarios as perfect fluid and dark fluid, where dark fluid term is derived in the form of perfect fluid source. We have made an observational constraint on the cosmological parameters [Formula: see text] and [Formula: see text] using [Formula: see text] test with observational datasets like Pantheon sample of SNe Ia and [Formula: see text]. With these constraints, we have discussed our model with deceleration parameter [Formula: see text], energy parameters [Formula: see text], EoS parameter [Formula: see text], etc. Als...

View PDFchevron_right

Related topics

  • Physics
  • Dark Energy
    • 580 California St., Suite 400
    San Francisco, CA, 94104
    © 2025 Academia. All rights reserved