Thawing versus tracker behaviour: observational evidence

Thakur, Shruti; Nautiyal, Akhilesh; Sen, Anjan A.; Seshadri, T. R.

doi:10.1111/j.1365-2966.2012.21988.x

Cited by 18 publications

(19 citation statements)

References 60 publications

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“…Hence with a single equation of state parametrization, one can model both the thawing as well as freezing class of scalar field models. Recently, this parametrization has been used [23] to study the Bayesian Evidence for thawing/freezing class of the dark energy models using different observational results including WMAP-7 results.…”

Section: Introductionmentioning

confidence: 99%

Post-Planck dark energy constraints

et al. 2015

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Abstract. We constrain plausible dark energy models, parametrized by multiple candidate equation of state, using the recently published Cosmic Microwave Background (CMB) temperature anisotropy data from Planck together with the WMAP-9 low-ℓ polarization data and data from low redshift surveys. To circumvent the limitations of any particular equation of state towards describing all existing dark energy models, we work with three different equation of state covering a broader class of dark energy models and, hence, provide more robust and generic constraints on the dark energy properties. We show that a clear tension exists between dark energy constraints from CMB and non-CMB observations when one allows for dark energy models having both phantom and non-phantom behavior; while CMB is more favorable to phantom models, the low-z data prefers model with behavior close to a Cosmological Constant. Further, we reconstruct the equation of state of dark energy as a function of redshift using the results from combined CMB and non-CMB data and find that Cosmological Constant lies outside the 1σ band for multiple dark energy models allowing phantom behavior. A considerable fine tuning is needed to keep models with strict non-phantom history inside 2σ allowed range. This result might motivate one to construct phantom models of dark energy, which is achievable in the presence of higher derivative operators as in string theory. However, disallowing phantom behavior, based only on strong theoretical prior, leads to both CMB and non-CMB datasets agree on the nature of dark energy, with the mean equation of state being very close to the Cosmological Constant. Finally, to illustrate the impact of additional dark energy parameters on other cosmological parameters, we provide the cosmological parameter constraints for the "Standard Model of Cosmology" including an evolving dark energy component, for the different dark energy models.

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Section: Introductionmentioning

confidence: 99%

Post-Planck dark energy constraints

et al. 2015

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“…Although a variety of potentials can give rise to both thawer and tracker potentials, it may be useful to have simple parametrization for the equation of state of the scalar field that broadly describes these two behaviours. The generalized chaplygin gas (GCG) equation of state described by p = −A/ρ α where A and α are two constant parameters, is useful for this purpose (Thakur et al 2012). For such a parametrization the dark energy equation of state is given by…”

Section: Thawing Vs Trackermentioning

confidence: 99%

“…We concentrate on the thawing class of scalar field models ( recent discussions argued that these are more favored than the tracking ones (Linder 2015) ). But to make the investigation complete, we also consider one particular parametrization (called GCG parametrization) (Thakur et al 2012) that broadly described both the thawing and tracker models and study the prospects of distinguishing these two behaviours using the HI intensity mapping survey by SKA. We also study the clustering on superhorizon scales where we can no longer ignore the scalar field fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Prospects of probing quintessence with H i 21-cm intensity mapping survey

Hussain¹,

Thakur²,

Sarkar³

et al. 2016

Mon. Not. R. Astron. Soc.

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We investigate the prospect of constraining scalar field dark energy models using HI 21-cm intensity mapping surveys. We consider a wide class of coupled scalar field dark energy models whose predictions about the background cosmological evolution are different from the ΛCDM predictions by a few percent. We find that these models can be statistically distinguished from ΛCDM through their imprint on the 21-cm angular power spectrum. At the fiducial z = 1.5, corresponding to a radio interferometric observation of the post-reionization HI 21 cm observation at frequency 568MHz, these models can infact be distinguished from the ΛCDM model at SNR > 3σ level using a 10,000 hr radio observation distributed over 40 pointings of a SKA1-mid like radio-telescope. We also show that tracker models are more likely to be ruled out in comparison with ΛCDM than the thawer models. Future radio observations can be instrumental in obtaining tighter constraints on the parameter space of dark energy models and supplement the bounds obtained from background studies.

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“…In this model, the equation of state of the scalar field is always very close to w = −1 and hence it behaves as dark energy without any fine tuning of the form of the potential, but one has to be fine tune the initial condition to get the right amount of scalar field energy density at present. One can use the different observational data to calculate the Bayesian Evidence for both thawing and freezing class of models [5]. The Bayesian Evidence is given by (5) where θ's are the model parameters, P (θ) is the prior probability distribution for the parameters θ's and L is the likelihood function.…”

Section: Dark Energy Modelsmentioning

confidence: 99%

“…If one considers the dark energy to be homogeneous, there is a significant evidence in favour of the thawing class of models. But assuming the dark energy to be clustered, both thawing and freezing class of models are equally preferres by the observational data [5].…”

Section: Dark Energy Modelsmentioning

confidence: 99%