Is the dynamics of scaling dark energy detectable?

Bassett, Bruce A.; Brownstone, Mike; Cardoso, António; Cortês, Marina; Fantaye, Y.; Hložek, Renée; Kotze, Jacques; Okouma, Patrice

doi:10.1088/1475-7516/2008/07/007

Cited by 25 publications

(19 citation statements)

References 33 publications

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“…allows dark energy to track the equation of state of radiation and matter and leads to acceleration at late times [36]. We shall use M 1 = 10 −14 m Pl , M 2 = 10 −13 m Pl , λ 1 = 9.43 and λ 2 = 1 which, as shown in [37], should give rise to observables that are significantly different from the cosmological constant but are still broadly consistent with observational constraints.…”

Section: Double Exponentialmentioning

confidence: 96%

A gauge-invariant approach to interactions in the dark sector

Potter

Chongchitnan

2011

J. Cosmol. Astropart. Phys.

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We outline a gauge-invariant framework to calculate cosmological perturbations in dark energy models consisting of a scalar field interacting with dark matter via energy and momentum exchanges. Focusing on three well-known models of quintessence and three common types of dark sector interactions, we calculate the matter and dark energy power spectra as well as the Integrated Sachs-Wolfe (ISW) effect in these models. We show how the presence of dark sector interactions can produce a large-scale enhancement in the matter power spectrum and a boost in the low multipoles of the cosmic microwave background anisotropies. Nevertheless, we find these enhancements to be much more subtle than those found by previous authors who model dark energy using simple ansatz for the equation of state. We also address issues of instabilities and emphasise the importance of momentum exchanges in the dark sector.

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Section: Double Exponentialmentioning

confidence: 96%

A gauge-invariant approach to interactions in the dark sector

Potter

Chongchitnan

2011

J. Cosmol. Astropart. Phys.

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“…One of the simplest and earliest parameterizations is the Taylor expansion of w z de ( ) with respect to redshift z up to first order as w z w w z de 0 1 = + ( ) (Maor et al 2001;Riess et al 2004). It can also be generalized by considering the second-order approximation in the Taylor series as w z w w z w z de 0 1 2 2 = + + ( ) (Bassett et al 2008). However, these two parameterizations diverge at high redshifts.…”

Section: Introductionmentioning

confidence: 99%

Constraints to Dark Energy Using PADE Parameterizations

Rezaei

Malekjani

Basilakos

et al. 2017

ApJ

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We put constraints on dark energy (DE) properties using PADE parameterization, and compare it to the same constraints using Chevalier-Polarski-Linder (CPL) and ΛCDM, at both the background and the perturbation levels. The DE equation of the state parameter of the models is derived following the mathematical treatment of PADE expansion. Unlike CPL parameterization, PADE approximation provides different forms of the equation of state parameter that avoid the divergence in the far future. Initially we perform a likelihood analysis in order to put constraints on the model parameters using solely background expansion data, and we find that all parameterizations are consistent with each other. Then, combining the expansion and the growth rate data, we test the viability of PADE parameterizations and compare them with CPL and ΛCDM models, respectively. Specifically, we find that the growth rate of the current PADE parameterizations is lower than ΛCDM model at low redshifts, while the differences among the models are negligible at high redshifts. In this context, we provide for the first time a growth index of linear matter perturbations in PADE cosmologies. Considering that DE is homogeneous, we recover the well-known asymptotic value of the growth index (namely . Finally, we generalize the growth index analysis in the case where γ is allowed to vary with redshift, and we find that the form of z g ( ) in PADE parameterization extends that of the CPL and ΛCDM cosmologies, respectively.

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“…We can estimate these values from the ΛCDM model if we put in corresponding expressions for the amounts of dark energy, matter and radiation today. The latter values should be in concordance with modern observational data, therefore we use values Ω [9,19,20]. We take this value as upper bound for dark energy contribution at initial time.…”

Section: Extension Of σCdm Model To Radiation Dominated Eramentioning

confidence: 86%

“…. In this paper we concentrated on case when initial value of dark energy equation of state parameter equals to 0 as in [9,19].…”

Section: Log(n)mentioning

confidence: 99%

σCDM coupled to radiation: Dark energy and Universe acceleration

2015

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Abstract. Recently the Chiral Cosmological Model (CCM) coupled to cold dark matter (CDM) has been investigated as σCDM model to study the observed accelerated expansion of the Universe. Dark sector fields (as Dark Energy content) coupled to cosmic dust were considered as the source of Einstein gravity in Friedmann-Robertson-Walker (FRW) cosmology. Such model had a beginning at the matter-dominated era. The purposes of our present investigation are two folds: to extend «life» of the σCDM for earlier times to radiation-dominated era and to take into account variation of the exponential potentialvia variation of the interaction parameter λ. We use Markov Chain Monte Carlo (MCMC) procedure to investigate possible values of initial conditions constrained by the measured amount of the dark matter, dark energy and radiation component today.Our analysis includes dark energy contribution to critical density, the ratio of the kinetic and potential energies, deceleration parameter, effective equation of state and evolution of DE equation of state with variation of coupling constant λ. A comparison with the ΛCDM model was performed. A new feature of the model is the existence of some values of potential coupling constant, leading to a σCDM solution without transit into accelerated expansion epoch.

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Is the dynamics of scaling dark energy detectable?

Cited by 25 publications

References 33 publications

A gauge-invariant approach to interactions in the dark sector

A gauge-invariant approach to interactions in the dark sector

Constraints to Dark Energy Using PADE Parameterizations

σCDM coupled to radiation: Dark energy and Universe acceleration

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