Constraining dark energy anisotropic stress

Mota, David F.; Kristiansen, Jørn; Koivisto, Tomi S.; Groeneboom, N. E.

doi:10.1111/j.1365-2966.2007.12413.x

Cited by 122 publications

(88 citation statements)

References 42 publications

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“…Moreover, the growth of cosmic structures are also affected by perturbations of DE when we deal with dynamical DE models with time varying EoS parameter w 1 de ¹ - (Erickson et al 2002;Bean & Doré 2004;Hu & Scranton 2004;Basilakos & Voglis 2007;Mota et al 2007;Ballesteros & Riotto 2008;Basilakos et al 2009aBasilakos et al , 2010Gannouji et al 2010;Sapone & Majerotto 2012;Batista & Pace 2013;Dossett & Ishak 2013;Basse et al 2014;Batista 2014;Nesseris & Sapone 2015;Pace et al 2014aPace et al , 2014bBasilakos 2015;Mehrabi et al 2015aMehrabi et al , 2015bMehrabi et al , 2015cMalekjani et al 2015Malekjani et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, we can set up a more general formalism in which the background expansion data, including SN Ia, BAO, CMB shift parameter, Hubble expansion data, joined with the growth rate data of LSSs in order to put constraints on the parameters of cosmology and DE models (see Cooray et al 2004;Corasaniti et al 2005;Mota et al 2007Mota et al , 2008Basilakos et al 2010;Gannouji et al 2010;Mota et al 2010;Blake et al 2011b;Nesseris et al 2011;Basilakos & Pouri 2012;Chuang et al 2013;Contreras et al 2013;Llinares & Mota 2013;Llinares et al 2014;Li et al 2014;Yang et al 2014;Basilakos 2015;Mehrabi et al 2015aMehrabi et al , 2015bBasilakos 2016;Bonilla Rivera & Farieta 2016;Fay 2016;Malekjani et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Constraints to Dark Energy Using PADE Parameterizations

Rezaei

Malekjani

Basilakos

et al. 2017

ApJ

Self Cite

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“…While a primordial shear decays if it is not sourced, late-time anisotropy appears in many phenomenological models of dark energy [3][4][5][6][7] and is a generic prediction of bigravity models [8] and backreaction [9]. Contrary to the former [10][11][12][13][14], the latter remains weakly constrained by the observation of the cosmic microwave background temperature field; this naturally stimulated analyses based, e.g., on the observation of supernovae [15][16][17][18][19][20][21][22][23][24][25][26][27], or using low-redshift galaxies [28,29].…”

Section: Introductionmentioning

confidence: 99%

Light propagation in a homogeneous and anisotropic universe

2015

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This article proposes a comprehensive analysis of light propagation in an anisotropic and spatially homogeneous Bianchi I universe. After recalling that null geodesics are easily determined in such a spacetime, we derive the expressions of the redshift and direction drifts of light sources; by solving analytically the Sachs equation, we then obtain an explicit expression of the Jacobi matrix describing the propagation of narrow light beams. As a by-product, we recover the old formula by Saunders for the angular diameter distance in a Bianchi I spacetime, but our derivation goes further since it also provides the optical shear and rotation. These results pave the way to the analysis of both supernovae data and weak lensing by the large-scale structure in Bianchi universes.

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“…Moreover, it could be used to distinguish among scalar field theories in which the possible nonminimal coupling occurs only at the perfect fluid matter sector [36][37][38][39]. Such perturbative shear stresses have in general been attempted to be constrained through parameters describing directly the difference of the metric variables [40] and the viscous properties of generalized fluids [41][42][43]. Unfortunately, the perturbative anisotropic stress could escape detection, when its influences are restricted to so large scales that they are only seen through the amplitude of the first few multipoles of the CMB.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic dark energy: dynamics of the background and perturbations

Koivisto

Mota

2008

J. Cosmol. Astropart. Phys.

179

168

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Abstract. We investigate cosmologies where the accelerated expansion of the Universe is driven by a field with an anisotropic equation of state. We model such scenarios within the Bianchi I framework, introducing two skewness parameters to quantify the deviation of pressure from isotropy. We study the dynamics of the background expansion in these models. A special case of anisotropic cosmological constant is analyzed in detail. The anisotropic expansion is then confronted with the redshift and angular distribution of the supernovae type Ia. In addition, we investigate the effects on the cosmic microwave background (CMB) anisotropies for which the main signature appears to be a quadrupole contribution. We find that the two skewness parameters can be very well constrained. Tightest bounds are imposed by the CMB quadrupole, but there are anisotropic models which avoid this bound completely. Within these bounds, the anisotropy can be beneficial as a potential explanation of various anomalous cosmological observations, especially in the CMB at the largest angles. We also consider the dynamics of linear perturbations in these models. The covariant approach is used to derive the general evolution equations for cosmological perturbations taking into account imperfect sources in an anisotropic background. The implications for the galaxy formation are then studied. These results might help to make contact between the observed anomalies in CMB and large scale structure and fundamental theories exhibiting Lorentz violation.

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Constraining dark energy anisotropic stress

Cited by 122 publications

References 42 publications

Constraints to Dark Energy Using PADE Parameterizations

Constraints to Dark Energy Using PADE Parameterizations

Light propagation in a homogeneous and anisotropic universe

Anisotropic dark energy: dynamics of the background and perturbations

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