Multiple-scales approach to the averaging problem in cosmology

نویسندگان

چکیده

The Universe is homogeneous and isotropic on large scales, so those scales it usually modelled as a Friedmann-Lemaítre-Robertson-Walker (FLRW) space-time. non-linearity of the Einstein field equations raises concern over averaging small-scale deviations form homogeneity isotropy, with possible implications applicability FLRW metric to Universe, even scales. Here I present technique, based multiple-scales method singular perturbation theory, handle inhomogeneities consistently. obtain leading order effective equation for large-scale space-time metric, which contains back-reaction term. derivation relies series consistency conditions, that ensure growth from do not grow unboundedly; criteria their satisfiability are discussed, shown they indeed satisfied if matter non-relativistic small analysis performed in harmonic gauge, conversion other gauges discussed. estimate magnitude term relative critical density example an NFW halo, find be few percent. In this example, interpreted contribution energy-density gravitational potential energy, averaged small-scale, total energy-momentum tensor.

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ژورنال

عنوان ژورنال: Journal of Cosmology and Astroparticle Physics

سال: 2021

ISSN: ['1475-7516', '1475-7508']

DOI: https://doi.org/10.1088/1475-7516/2021/02/049