A Modified Gravity Theory: Null Aether*

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buir.contributor.authorGürses, Metin
buir.contributor.authorŞentürk, Çetin
dc.citation.epage326en_US
dc.citation.issueNumber3en_US
dc.citation.spage312en_US
dc.citation.volumeNumber73en_US
dc.contributor.authorGürses, Metinen_US
dc.contributor.authorŞentürk, Çetinen_US
dc.date.accessioned2020-02-05T12:47:00Z
dc.date.available2020-02-05T12:47:00Z
dc.date.issued2019-03
dc.departmentDepartment of Mathematicsen_US
dc.departmentDepartment of Physicsen_US
dc.description.abstractGeneral quantum gravity arguments predict that Lorentz symmetry might not hold exactly in nature. This has motivated much interest in Lorentz breaking gravity theories recently. Among such models are vector-tensor theories with preferred direction established at every point of spacetime by a fixed-norm vector field. The dynamical vector field defined in this way is referred to as the “aether”. In this paper, we put forward the idea of a null aether field and introduce, for the first time, the Null Aether Theory (NAT) — a vector-tensor theory. We first study the Newtonian limit of this theory and then construct exact spherically symmetric black hole solutions in the theory in four dimensions, which contain Vaidya-type non-static solutions and static Schwarzschild-(A)dS type solutions, Reissner-Nordstr¨om-(A)dS type solutions and solutions of conformal gravity as special cases. Afterwards, we study the cosmological solutions in NAT: We find some exact solutions with perfect fluid distribution for spatially flat FLRW metric and null aether propagating along the x direction. We observe that there are solutions in which the universe has big-bang singularity and null field diminishes asymptotically. We also study exact gravitational wave solutions — AdS-plane waves and pp-waves — in this theory in any dimension D ≥ 3. Assuming the Kerr-Schild-Kundt class of metrics for such solutions, we show that the full field equations of the theory are reduced to two, in general coupled, differential equations when the background metric assumes the maximally symmetric form. The main conclusion of these computations is that the spin-0 aether field acquires a “mass” determined by the cosmological constant of the background spacetime and the Lagrange multiplier given in the theory.en_US
dc.description.sponsorshipTÜBİTAKen_US
dc.identifier.doi10.1088/0253-6102/71/3/312en_US
dc.identifier.eissn1572-9494
dc.identifier.issn0253-6102
dc.identifier.urihttp://hdl.handle.net/11693/53096
dc.language.isoEnglishen_US
dc.publisherChinese Physical Society and IOP Publishingen_US
dc.relation.isversionofhttps://doi.org/10.1088/0253-6102/71/3/312en_US
dc.source.titleCommunications in Theoretical Physicsen_US
dc.subjectAether theoryen_US
dc.subjectNewtonian limiten_US
dc.subjectBlack holesen_US
dc.subjectCosmological solutionsen_US
dc.subjectKerr-Schild-Kundt class of metricsen_US
dc.subjectAds-plane wavesen_US
dc.subjectpp-wavesen_US
dc.titleA Modified Gravity Theory: Null Aether*en_US
dc.typeArticleen_US

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