Geometric optics in relativistic cosmology: New formulation and a new observable

• DOI: 10.1103/physrevd.101.063506
• Publication Date: 2020-03-09T13:57:04Z
• Authors: Mikołaj Korzyński; Eleonora Villa
• Keywords: Parallax; Observer (physics); Geometrical optics

We discuss a new formalism for light propagation which can be used within the regime of validity geometric optics, but with no limitation on scales interest: from inside Galaxy to ultralarge cosmology. One our main results is that this framework it possible calculate all relevant observables (image magnification, parallax, position drift or proper motion) by simply differentiating photon trajectory respect initial data. then focus observable, we name distance slip: defined as relative difference between angular diameter and parallax distance. Its peculiarity lies in fact its value independent momentary motions both source observer short distances shows tomographic property, being proportional amount matter along line sight. After describing further properties methods measurement, specialize study slip show does not depend Hubble constant ${H}_{0}$ dependence other cosmological parameters different indicators. This suggests may contain information.