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arXiv · 1812.03671

Observation angles, Fermi coordinates, and the Geodesic-Light-Cone gauge

Giuseppe Fanizza·Maurizio Gasperini·Giovanni Marozzi·Gabriele Veneziano
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Abstract

We show that the angular directions locally measured by a static geodesic observer in a generic cosmological background and expressed in the system of Fermi Normal Coordinates always coincide with those expressed in the Geodesic-Light-Cone (GLC) gauge, up to a local transformation which exploits the residual gauge freedom of the GLC coordinates. This is not the case for other gauges - like, for instance, the synchronous and longitudinal gauge - commonly used in the context of observational cosmology. We also make an explicit proposal for the GLC gauge-fixing condition that ensures a full identification of its angles with the observational ones.

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Giuseppe Fanizza, Maurizio Gasperini, Giovanni Marozzi, Gabriele Veneziano. 2018-12-10. Observation angles, Fermi coordinates, and the Geodesic-Light-Cone gauge. https://doi.org/10.1088/1475-7516%2F2019%2F01%2F004

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