The growth of DM and DE perturbations in DBI non-canonical scalar field scenario

Rezazadeh, K.; Asadzadeh, Seyed Mohammad; Fahimi, K.; Karami, K.; Mehrabi, Ahmad

doi:10.1016/j.aop.2020.168299

Cited by 6 publications

(4 citation statements)

References 86 publications

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“…These equations are in agreement with the equations that are used to study the largestructure formation in the Newtonian regime of perturbations (see, e.g., [11,[41][42][43][44][45][46]).…”

Section: Cosmological Perturbationssupporting

confidence: 72%

“…In order to investigate the evolution of density perturbation in the linear regime, we solve numerically the quadratic differential equation of δ for each case of our model by using the best-fit values of its parameters reported in Table I. Since, the space-time perturbations are assumed to be adiabatic during the Universe evolution in our scenario, then we take c 2 eff = c 2 s [46]. With this assumption, one can solve the coupled differential equations ( 44) and ( 44), numerically.…”

Section: Growth Factormentioning

confidence: 99%

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Structure Formation in Dark Matter Particle Production Cosmology

Safari,

Rezazadeh,

Malekolkalami

2022

Preprint

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We investigate a cosmological scenario in which the dark matter particles can be created during the evolution of the Universe. By regarding the Universe as an open thermodynamic system and using non-equilibrium thermodynamics, we examine the mechanism of gravitational particle production. In this setup, we study the large-scale structure (LSS) formation of the Universe in the Newtonian regime of perturbations and derive the equations governing the evolution of the dark matter overdensities. Then, we implement the cosmological data from Planck 2018 CMB measurements, SNe Ia and BAO observations, as well as the SH0ES local measurement for H 0 to provide some cosmological constraints for the parameters of our model. We see that the best case of our scenario (χ 2 tot = 3834.40) fits the observational data better than the baseline ΛCDM model (χ 2 tot = 3838.00) at the background level. We also see that this case results in the Hubble constant as H 0 = 68.79 ± 0.59 km s −1 Mpc −1 which is greater than H 0 = 68.20 +0.42 −0.38 km s −1 Mpc −1 given by the ΛCDM model, and hence we can alleviate the H 0 tension to some extent in our framework. Furthermore, the best case of our scenario gives a lower value for the best-fit of the S 8 parameter than the ΛCDM result, and therefore it also reduces the LSS tension slightly. We moreover estimate the growth factor of linear perturbations and show that the best case of our model (χ 2 f σ 8 = 40.84) fits the LSS data significantly better than the ΛCDM model (χ 2 f σ 8 = 44.29). Consequently, our model also makes a better performance at the level of the linear perturbations compared to the standard cosmological model.

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“…These equations are in agreement with the equations that are used to study the largestructure formation in the Newtonian regime of perturbations (see, e.g., [11,[41][42][43][44][45][46]).…”

Section: Cosmological Perturbationssupporting

confidence: 72%

Section: Growth Factormentioning

confidence: 99%

Structure Formation in Dark Matter Particle Production Cosmology

Safari,

Rezazadeh,

Malekolkalami

2022

Preprint

Self Cite

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“…Generally speaking, all theoretical models have some free parameters which should be constrained by an observational data. So having a model and some observational data, it is an easy task to perform a statistical parameter inference to obtain the free parameters as well as their uncertainties [27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of dark energy density by non-parametric approaches

Mehrabi¹,

Vazirnia²

2022

Preprint

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The evolution of dark energy density is a crucial quantity in understanding the nature of dark energy. Often, the quantity is described by the so called equation of state, that is the ratio of dark energy pressure to its density. In this scenario, the dark energy density is always positive throughout the cosmic history and a negative value is not allowed. Assuming a homogeneous and isotropic universe, we reconstruct the dark energy density directly from observational data and investigate its evolution through cosmic history. We consider the latest SNIa, BAO and cosmic chronometer data and reconstruct the dark energy density in both flat and non-flat universes up to redshift z ∼ 3. The results are well in agreement with the ΛCDM up to redshift z ∼ 1.5, whereas all data and methods, in our analysis, provide a negative dark energy density at high redshifts.

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“…Generally speaking, all theoretical models have some free parameters that should be constrained by observational data. So, with a model and some observational data, it is an easy task to perform a statistical parameter inference to obtain the free parameters, as well as their uncertainties (Mehrabi et al 2015;Rezaei et al 2017;Mehrabi 2018;Mehrabi & Basilakos 2018;Rezazadeh et al 2020;Rezaei et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Model-independent Reconstruction of Dark Energy Density from Current Observations

Mehrabi

Vazirnia

2022

ApJ

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The evolution of the dark energy (DE) density is a crucial quantity for understanding the nature of DE. Often, the quantity is described by the so-called equation of state; that is, the ratio of the DE pressure to its density. In this scenario, the DE density is always positive throughout cosmic history, and a negative value is not allowed. Assuming a homogeneous and isotropic universe, we reconstruct the DE density directly from observational data and investigate its evolution throughout cosmic history. We consider the latest Type Ia supernova, baryon acoustic oscillation, and cosmic chronometer data, and reconstruct the DE density in both flat and nonflat universes up to redshift z ∼ 3. The results are well in agreement with ΛCDM up to redshift z ∼ 1.5, but we see a weak sign of negative DE density at high redshifts.

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The growth of DM and DE perturbations in DBI non-canonical scalar field scenario

Cited by 6 publications

References 86 publications

Structure Formation in Dark Matter Particle Production Cosmology

Structure Formation in Dark Matter Particle Production Cosmology

Reconstruction of dark energy density by non-parametric approaches

Model-independent Reconstruction of Dark Energy Density from Current Observations

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