We consider a recent approach to the construction of gauge-invariant relational
observables in gravity in the context of cosmological perturbation theory. These observables
are constructed using a field-dependent coordinate system, which we take to be geodesic
lightcone coordinates. We show that the observables are gauge-independent in the fully nonlinear theory, and that they have the expected form when one adopts the geodesic lightcone
gauge for the metric. We give explicit expressions for the Sasaki-Mukhanov variable at linear
order, and the Hubble rate — as measured both by geodesic observers and by observers
co-moving with the inflaton — to second order. Moreover, we show that the well-known
linearised equations of motion for the Sasaki-Mukhanov variable and the scalar constraint
variables follow from the gauge-invariant Einstein’s equations
Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:85195 |
Date | 04 May 2023 |
Creators | Fröb, Markus B., Lima, William C.C. |
Publisher | IOP Publishing |
Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
Language | English |
Detected Language | English |
Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
Rights | info:eu-repo/semantics/openAccess |
Relation | 1475-7516, 034 |
Page generated in 0.0022 seconds