Inhomogeneous and Interacting Vacuum Energy

De-Santiago, Josué; Wands, David; Wang, Yuting

doi:10.1007/978-3-319-02063-1_13

Cited by 13 publications

(21 citation statements)

References 70 publications

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“…Such a correction could be viewed as a non-constant 'dark energy' cosmological term. Such non-constant terms are not conserved but nevertheless could have a dynamic or 'interacting vacuum' cosmological interpretation [10]. There may, however, be other corrections to the classical Einstein tensor coming from the identification of the tensors (this requires a fuller semiclassical analysis).…”

Section: Summary and Discussionmentioning

confidence: 99%

Gravity induced from quantum spacetime

Beggs¹,

Majid²

2014

Class. Quantum Grav.

212

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Abstract. We show that tensoriality constraints in noncommutative Riemannian geometry in the 2-dimensional bicrossproduct model quantum spacetime algebra [x, t] = λx drastically reduce the moduli of possible metrics g up to normalisation to a single real parameter which we interpret as a time in the past from which all timelike geodesics emerge and a corresponding time in the future at which they all converge. Our analysis also implies a reduction of moduli in n-dimensions and we study the suggested spherically symmetric classical geometry in n = 4 in detail, identifying two 1-parameter subcases where the Einstein tensor matches that of a perfect fluid for (a) positive pressure, zero density and (b) negative pressure and positive density with ratio w Q = − 1 2 . The classical geometry is conformally flat and its geodesics motivate new coordinates which we extend to the quantum case as a new description of the quantum spacetime model as a quadratic algebra. The noncommutative Riemannian geometry is fully solved for n = 2 and includes the quantum Levi-Civita connection and a second, nonperturbative, Levi-Civita connection which blows up as λ → 0. We also propose a 'quantum Einstein tensor' which is identically zero for the main part of the moduli space of connections (as classically in 2D). However, when the quantum Ricci tensor and metric are viewed as deformations of their classical counterparts there would be an O(λ 2 ) correction to the classical Einstein tensor and an O(λ) correction to the classical metric.

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Section: Summary and Discussionmentioning

confidence: 99%

Gravity induced from quantum spacetime

Beggs¹,

Majid²

2014

Class. Quantum Grav.

212

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“…5 In IDM with a vanishing sound speed, the fluid elements always follow geodesics of the space time (see e.g. [24] or the geodesic choice for the models of [51,52] for such a model). Therefore the infall is the same as for the CDM initially.…”

Section: Structures Large and Small In Idmmentioning

confidence: 99%

Seeding supermassive black holes with a nonvortical dark-matter subcomponent

2013

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A perfect irrotational fluid with the equation of state of dust, irrotational dark matter (IDM), is incapable of virializing and instead forms a cosmoskeleton of filaments with supermassive black holes at the joints. This stark difference from the standard cold dark matter scenario arises because IDM must exhibit potential flow at all times, preventing shell crossing from occurring. This scenario is applicable to general nonoscillating scalar-field theories with a small sound speed. Our model of combined IDM and cold dark matter components thereby provides a solution to the problem of forming the observed billionsolar-mass black holes at redshifts of six and higher. In particular, as a result of the reduced vortical flow, the growth of the black holes is expected to be more rapid at later times as compared to the standard scenario.

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“…Recent studies of interacting vacuum cosmologies have focused on specific models for the interaction, QðzÞ [17][18][19][20][21]. In this Letter we want to consider a general interaction QðzÞ in different redshift bins.…”

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confidence: 99%

Indications of a Late-Time Interaction in the Dark Sector

et al. 2014

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We show that a general late-time interaction between cold dark matter and vacuum energy is favored by current cosmological data sets. We characterize the strength of the coupling by a dimensionless parameter q(V) that is free to take different values in four redshift bins from the primordial epoch up to today. This interacting scenario is in agreement with measurements of cosmic microwave background temperature anisotropies from the Planck satellite, supernovae Ia from Union 2.1 and redshift space distortions from a number of surveys, as well as with combinations of these different data sets. Our analysis of the 4-bin interaction shows that a nonzero interaction is likely at late times. We then focus on the case q(V)≠0 in a single low-redshift bin, obtaining a nested one parameter extension of the standard ΛCDM model. We study the Bayesian evidence, with respect to ΛCDM, of this late-time interaction model, finding moderate evidence for an interaction starting at z=0.9, dependent upon the prior range chosen for the interaction strength parameter q(V). For this case the null interaction (q(V)=0, i.e., ΛCDM) is excluded at 99% C.L.

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Inhomogeneous and Interacting Vacuum Energy

Cited by 13 publications

References 70 publications

Gravity induced from quantum spacetime

Gravity induced from quantum spacetime

Seeding supermassive black holes with a nonvortical dark-matter subcomponent

Indications of a Late-Time Interaction in the Dark Sector

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