Model independent approach to the dark energy equation of state

Corasaniti, Pier-Stefano; Copeland, Edmund J.

doi:10.1103/physrevd.67.063521

Cited by 181 publications

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“…Our task has been made easier by the availability of parametrizations which accurately describe the dynamics of the different quintessence models (Corasaniti & Copeland, 2003;Linder & Huterer, 2005). This allows In this thesis we have taken into account three levels of modification from a ΛCDM cosmology which are necessary if we wish to faithfully incorporate the effects of quintessence dark energy into a N-body simulation.…”

Section: Discussionmentioning

confidence: 99%

“…The equation for w valid after matter-radiation equality is Copeland (2003) showed that this four parameter fit gives an excellent match to the exact equation of state. Table 3.1 gives the best fit values for the equation of state parameters for the different quintessence models taken from Corasaniti & Copeland (2003), with the addition of the INV2 model. The parametrization for the dark energy equation of state is plotted in Fig.…”

Section: Parametrization Of Wmentioning

confidence: 99%

“…A general prescription for w(z) containing more parameters than a simple 1 or 2 variable equation can accurately describe both slowly and rapidly varying equations of state . For example, the parametrization provided by Corasaniti & Copeland (2003) can accurately mimic the exact time behaviour of w(z) to < 5% for z < 10 3 using a 4 parameter equation of state and to < 9% for z < 10 5 with a 6 parameter equation. Finally, we note that the parametrization for w proposed by Corasaniti & Copeland (2003) is similar to the four parameter equation of state in Linder & Huterer (2005) (Model 4.0) where the evolution of w is described in terms of the e-fold variable, N = ln a, where a is the scale factor.…”

Section: Parametrization Of Wmentioning

confidence: 99%

“…Throughout this chapter we will employ the parametrization for w proposed by Corasaniti & Copeland (2003), which is a generalisation of the method used by Bassett et al (2002) for fitting dark energy models with rapid late time transitions.…”

Section: Parametrization Of Wmentioning

confidence: 99%

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Simulations of Dark Energy Cosmologies

Jennings

2012

Springer Theses

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. No part of this thesis has been submitted elsewhere for any other degree or qualification.The work of others has been duly acknowledged.The copyright of this thesis rests with the author. No quotations from it should be published without the author's prior written consent and information derived from it should be acknowledged. AbstractFuture galaxy redshift surveys will make high precision measurements of the cosmic expansion history and the growth of structure which will potentially allow us to distinguish between different scenarios for the accelerating expansion of the Universe. In this thesis we study the nonlinear growth of cosmic structure in different dark energy models, using ultra-large volume N-body simulations. We measure key observables such as the growth of large scale structure, the halo mass function and baryonic acoustic oscillations.We study the power spectrum in redshift space in ΛCDM and quintessence dark energy models and test predictions for the form of the redshift space distortions. An improved model for the redshift space power spectrum, including the non-linear velocity divergence power spectrum, is presented. We have found a density-velocity relation which is cosmology independent and which relates the non-linear velocity divergence spectrum to the non-linear matter power spectrum. We provide a formula which generates the non-linear velocity divergence P(k) at any redshift, using only the non-linear matter power spectrum and the linear growth factor at the desired redshift. We also demonstrate for the first time that competing cosmological models with identical expansion histories -one with a scalar field and the other with a time-dependent change to Newton's gravitational constant -can indeed be distinguished by a measurement of the rate at which structures grow.Our calculations show that linear theory models for the power spectrum in redshift space fail to recover the correct growth rate on surprisingly large scales, leading to catastrophic systematic errors. Improved theoretical models, which have been calibrated against simulations, are needed to exploit the exquisitely accurate clustering measurements expected from future surveys.

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Section: Discussionmentioning

confidence: 99%

Section: Parametrization Of Wmentioning

confidence: 99%

Section: Parametrization Of Wmentioning

confidence: 99%

Section: Parametrization Of Wmentioning

confidence: 99%

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Simulations of Dark Energy Cosmologies

Jennings

2012

Springer Theses

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“…A combined large scale structure (LSS), SNe, and CMB analysis has set an upper limit on Q-models with a constant w φ < −0.7 [4], and a more recent analysis of CMB observations gives w φ = −0.82 +0.14 −0.11 [5]. Furthermore, the SNe data and measurements of the position of the acoustic peaks in the CMB anisotropy spectrum have been used to put a constraint on the present w 0 φ ≤ −0.96 [6].The apparent brightness of the farthest SN observed to date, SN1997ff at redshift z ∼ 1.7, is consistent with that expected in the decelerating phase of the flat ΛCDM model with Ω Λ ≃ 0.7 [7], inferring w φ = −1 for z < 1.7. In addition, several attempts have been made to test different Q-models [8].…”

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Primordial magnetic fields from dark energy

Lee

2002

Physics Letters B

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Evidences indicate that the dark energy constitutes about two thirds of the critical density of the universe. If the dark energy is an evolving pseudo scalar field that couples to electromagnetism, a cosmic magnetic seed field can be produced via spinoidal instability during the formation of largescale structures. PACS number(s): 98.35. Eg, 98.80.Cq Recent astrophysical and cosmological observations such as dynamical mass, Type Ia supernovae (SNe), gravitational lensing, and cosmic microwave background (CMB) anisotropies, concordantly prevail a spatially flat universe containing a mixture of matter and a dominant smooth component with effective negative pressure [1]. The simplest possibility for this component is a cosmological constant. A dynamical variation calls for the existence of dark energy whose equation of state approaches that of the cosmological constant at recent epochs. Many possibilities have been proposed to explain for the dark energy. Most of the dark energy models involve the dynamical evolution of classical scalar fields or quintessence (Q). For a Q-model, the dynamics is governed by the scalar field potential such that the vacuum energy becomes dynamically important only at recent epochs and gives rise to an effective cosmological constant today. So far, many different kinds of scalar field potentials have been proposed. They include pseudo Nambu-Goldstone boson (PNGB), inverse power law, exponential, tracking oscillating, and others [2]. Upcoming observations will measure the equation of state so as to discriminate between these models and distinguish them from the cosmological constant [3].Since the scalar potential V (φ) of the Q field is scarcely known, it is convenient to discuss the evolution of φ through the equation of state, p φ = w φ ρ φ . Physically, 1 ≥ w φ ≥ −1, where the latter equality holds for a pure vacuum state. Lately some progress has been made in constraining the behavior of Q fields from observational data. A combined large scale structure (LSS), SNe, and CMB analysis has set an upper limit on Q-models with a constant w φ < −0.7 [4], and a more recent analysis of CMB observations gives w φ = −0.82 +0.14 −0.11 [5]. Furthermore, the SNe data and measurements of the position of the acoustic peaks in the CMB anisotropy spectrum have been used to put a constraint on the present w 0 φ ≤ −0.96 [6].The apparent brightness of the farthest SN observed to date, SN1997ff at redshift z ∼ 1.7, is consistent with that expected in the decelerating phase of the flat ΛCDM model with Ω Λ ≃ 0.7 [7], inferring w φ = −1 for z < 1.7. In addition, several attempts have been made to test different Q-models [8]. Nevertheless, it is primitive to differentiate between the variations, and the reconstruction of V (φ) would require next-generation observations.Although the physical state of the dark energy can be probed through its gravitational effects on the cosmological evolution, it is important in fundamental physics to understand whether the quintessence is a nearly massless, slowing rolling...

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Massive Neutrinos Meet (Non-Phantom) Dark Energy

Vagnozzi

2020

Weigh Them All!

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Model independent approach to the dark energy equation of state

Cited by 181 publications

References 52 publications

Simulations of Dark Energy Cosmologies

Simulations of Dark Energy Cosmologies

Primordial magnetic fields from dark energy

Massive Neutrinos Meet (Non-Phantom) Dark Energy

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