The $\Lambda$ to zero limit of spacetimes and its physical interpretation

Bugden, Mark; Paganini, Claudio F.

doi:10.1088/1361-6382/aaff0d

Cited by 3 publications

(2 citation statements)

References 38 publications

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“…(2.61) 26 Recall that an exact sequence is one in which the image of each map is equal to the kernel of the following map. 27 Note that for the remainder of this section we will suppress the Z in H k (M, Z).…”

Section: Description Using Gysin Sequencesmentioning

confidence: 99%

A Tour of T-duality: Geometric and Topological Aspects of T-dualities

Bugden¹

2019

Preprint

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The primary focus of this thesis is to investigate the mathematical and physical properties of spaces that are related by T-duality and its generalisations. In string theory, T-duality is a relationship between two a priori different string backgrounds which nevertheless behave identically from a physical point of view. These backgrounds can have different geometries, different fluxes, and even be topologically distinct manifolds. T-duality is a uniquely 'stringy' phenomenon, since it does not occur in a theory of point particles, and together with other dualities has been incredibly useful in elucidating the nature of string theory and M-theory.There exist various generalisations of the usual T-duality, some of which are still putative, and none of which are fully understood. Some of these dualities are inspired by mathematics and some are inspired by physics. These generalisations include non-abelian T-duality, Poisson-Lie T-duality, non-isometric T-duality, and spherical T-duality. In this thesis we review T-duality and its various generalisations, studying the geometric, topological, and physical properties of spaces related by these dualities.

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Section: Description Using Gysin Sequencesmentioning

confidence: 99%

A Tour of T-duality: Geometric and Topological Aspects of T-dualities

Bugden¹

2019

Preprint

Self Cite

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“…The limits that we consider in this paper are smooth limits of metric functions defined specifically in some coordinate systems. See for example[32] for a limiting procedure that covariantizes the process by lifting the spacetime to a higher-dimensional one with the metric parameter as an auxiliary dimension, and then taking its boundary 5. This algorithm is typically applied with the assumption of asymptotic flatness in the generated metric which does not hold for our solution though.…”

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confidence: 99%

Shadows of Kerr–Vaidya-like black holes

Tan

2023

Class. Quantum Grav.

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In this work, we study the shadow boundary curves of rotating time-dependent black hole solutions which have well-deﬁned Kerr and Vaidya limits. These solutions are constructed by applying the Newman-Janis algorithm to a spherically symmetric seed metric conformal to the Vaidya solution with a mass function that is linear in Eddington-Finkelstein coordinates. Equipped with a conformal Killing vector ﬁeld, this class of solution exhibits separability of null geodesics, thus allowing one to develop an analytic formula for the boundary curve of its shadow. We ﬁnd a simple power law describing the dependence of the mean radius and asymmetry factor of the shadow on the accretion rate. Applicability of our model to recent Event Horizon Telescope observations of M87∗ and Sgr A∗ is also discussed.

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On the cosmological constant as a quantum operator

Córdoba

Torrome

Gavasso

et al. 2022

Int. J. Geom. Methods Mod. Phys.

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We regard the cosmological fluid within an exponentially expanding FLRW spacetime as the probability fluid of a nonrelativistic Schroedinger field. The scalar Schroedinger particle so described has a mass equal to the total (baryonic plus dark) matter content of the Universe. This procedure allows a description of the cosmological fluid by means of the operator formalism of nonrelativistic quantum theory. Under the assumption of radial symmetry, a quantum operator proportional to [Formula: see text] represents the cosmological constant [Formula: see text]. The experimentally measured value of [Formula: see text] is one of the eigenvalues of [Formula: see text]. Next we solve the Poisson equation [Formula: see text] for the gravitational potential [Formula: see text], with the cosmological constant [Formula: see text] playing the role of a source term. It turns out that [Formula: see text] includes, besides the standard Newtonian potential [Formula: see text], a correction term proportional to [Formula: see text] identical to that appearing in theories of modified Newtonian dynamics.

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The $\Lambda$ to zero limit of spacetimes and its physical interpretation

Cited by 3 publications

References 38 publications

A Tour of T-duality: Geometric and Topological Aspects of T-dualities

A Tour of T-duality: Geometric and Topological Aspects of T-dualities

Shadows of Kerr–Vaidya-like black holes

On the cosmological constant as a quantum operator

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